Merge branch 'v2-prototype' into eth-lightwallet-subprovider-final

63 files changed, 7750 insertions, 0 deletions

diff --git a/packages/contracts/src/2.0.0/multisig/MultiSigWallet.sol b/packages/contracts/src/2.0.0/multisig/MultiSigWallet.sol
new file mode 100644
index 000000000..79fd92029
--- /dev/null
+++ b/packages/contracts/src/2.0.0/multisig/MultiSigWallet.sol
@@ -0,0 +1,365 @@
+pragma solidity ^0.4.10;
+
+/// @title Multisignature wallet - Allows multiple parties to agree on transactions before execution.
+/// @author Stefan George - <stefan.george@consensys.net>
+contract MultiSigWallet {
+
+    uint constant public MAX_OWNER_COUNT = 50;
+
+    event Confirmation(address indexed sender, uint indexed transactionId);
+    event Revocation(address indexed sender, uint indexed transactionId);
+    event Submission(uint indexed transactionId);
+    event Execution(uint indexed transactionId);
+    event ExecutionFailure(uint indexed transactionId);
+    event Deposit(address indexed sender, uint value);
+    event OwnerAddition(address indexed owner);
+    event OwnerRemoval(address indexed owner);
+    event RequirementChange(uint required);
+
+    mapping (uint => Transaction) public transactions;
+    mapping (uint => mapping (address => bool)) public confirmations;
+    mapping (address => bool) public isOwner;
+    address[] public owners;
+    uint public required;
+    uint public transactionCount;
+
+    struct Transaction {
+        address destination;
+        uint value;
+        bytes data;
+        bool executed;
+    }
+
+    modifier onlyWallet() {
+        if (msg.sender != address(this))
+            throw;
+        _;
+    }
+
+    modifier ownerDoesNotExist(address owner) {
+        if (isOwner[owner])
+            throw;
+        _;
+    }
+
+    modifier ownerExists(address owner) {
+        if (!isOwner[owner])
+            throw;
+        _;
+    }
+
+    modifier transactionExists(uint transactionId) {
+        if (transactions[transactionId].destination == 0)
+            throw;
+        _;
+    }
+
+    modifier confirmed(uint transactionId, address owner) {
+        if (!confirmations[transactionId][owner])
+            throw;
+        _;
+    }
+
+    modifier notConfirmed(uint transactionId, address owner) {
+        if (confirmations[transactionId][owner])
+            throw;
+        _;
+    }
+
+    modifier notExecuted(uint transactionId) {
+        if (transactions[transactionId].executed)
+            throw;
+        _;
+    }
+
+    modifier notNull(address _address) {
+        if (_address == 0)
+            throw;
+        _;
+    }
+
+    modifier validRequirement(uint ownerCount, uint _required) {
+        if (   ownerCount > MAX_OWNER_COUNT
+            || _required > ownerCount
+            || _required == 0
+            || ownerCount == 0)
+            throw;
+        _;
+    }
+
+    /// @dev Fallback function allows to deposit ether.
+    function()
+        payable
+    {
+        if (msg.value > 0)
+            Deposit(msg.sender, msg.value);
+    }
+
+    /*
+     * Public functions
+     */
+    /// @dev Contract constructor sets initial owners and required number of confirmations.
+    /// @param _owners List of initial owners.
+    /// @param _required Number of required confirmations.
+    function MultiSigWallet(address[] _owners, uint _required)
+        public
+        validRequirement(_owners.length, _required)
+    {
+        for (uint i=0; i<_owners.length; i++) {
+            if (isOwner[_owners[i]] || _owners[i] == 0)
+                throw;
+            isOwner[_owners[i]] = true;
+        }
+        owners = _owners;
+        required = _required;
+    }
+
+    /// @dev Allows to add a new owner. Transaction has to be sent by wallet.
+    /// @param owner Address of new owner.
+    function addOwner(address owner)
+        public
+        onlyWallet
+        ownerDoesNotExist(owner)
+        notNull(owner)
+        validRequirement(owners.length + 1, required)
+    {
+        isOwner[owner] = true;
+        owners.push(owner);
+        OwnerAddition(owner);
+    }
+
+    /// @dev Allows to remove an owner. Transaction has to be sent by wallet.
+    /// @param owner Address of owner.
+    function removeOwner(address owner)
+        public
+        onlyWallet
+        ownerExists(owner)
+    {
+        isOwner[owner] = false;
+        for (uint i=0; i<owners.length - 1; i++)
+            if (owners[i] == owner) {
+                owners[i] = owners[owners.length - 1];
+                break;
+            }
+        owners.length -= 1;
+        if (required > owners.length)
+            changeRequirement(owners.length);
+        OwnerRemoval(owner);
+    }
+
+    /// @dev Allows to replace an owner with a new owner. Transaction has to be sent by wallet.
+    /// @param owner Address of owner to be replaced.
+    /// @param owner Address of new owner.
+    function replaceOwner(address owner, address newOwner)
+        public
+        onlyWallet
+        ownerExists(owner)
+        ownerDoesNotExist(newOwner)
+    {
+        for (uint i=0; i<owners.length; i++)
+            if (owners[i] == owner) {
+                owners[i] = newOwner;
+                break;
+            }
+        isOwner[owner] = false;
+        isOwner[newOwner] = true;
+        OwnerRemoval(owner);
+        OwnerAddition(newOwner);
+    }
+
+    /// @dev Allows to change the number of required confirmations. Transaction has to be sent by wallet.
+    /// @param _required Number of required confirmations.
+    function changeRequirement(uint _required)
+        public
+        onlyWallet
+        validRequirement(owners.length, _required)
+    {
+        required = _required;
+        RequirementChange(_required);
+    }
+
+    /// @dev Allows an owner to submit and confirm a transaction.
+    /// @param destination Transaction target address.
+    /// @param value Transaction ether value.
+    /// @param data Transaction data payload.
+    /// @return Returns transaction ID.
+    function submitTransaction(address destination, uint value, bytes data)
+        public
+        returns (uint transactionId)
+    {
+        transactionId = addTransaction(destination, value, data);
+        confirmTransaction(transactionId);
+    }
+
+    /// @dev Allows an owner to confirm a transaction.
+    /// @param transactionId Transaction ID.
+    function confirmTransaction(uint transactionId)
+        public
+        ownerExists(msg.sender)
+        transactionExists(transactionId)
+        notConfirmed(transactionId, msg.sender)
+    {
+        confirmations[transactionId][msg.sender] = true;
+        Confirmation(msg.sender, transactionId);
+        executeTransaction(transactionId);
+    }
+
+    /// @dev Allows an owner to revoke a confirmation for a transaction.
+    /// @param transactionId Transaction ID.
+    function revokeConfirmation(uint transactionId)
+        public
+        ownerExists(msg.sender)
+        confirmed(transactionId, msg.sender)
+        notExecuted(transactionId)
+    {
+        confirmations[transactionId][msg.sender] = false;
+        Revocation(msg.sender, transactionId);
+    }
+
+    /// @dev Allows anyone to execute a confirmed transaction.
+    /// @param transactionId Transaction ID.
+    function executeTransaction(uint transactionId)
+        public
+        notExecuted(transactionId)
+    {
+        if (isConfirmed(transactionId)) {
+            Transaction tx = transactions[transactionId];
+            tx.executed = true;
+            if (tx.destination.call.value(tx.value)(tx.data))
+                Execution(transactionId);
+            else {
+                ExecutionFailure(transactionId);
+                tx.executed = false;
+            }
+        }
+    }
+
+    /// @dev Returns the confirmation status of a transaction.
+    /// @param transactionId Transaction ID.
+    /// @return Confirmation status.
+    function isConfirmed(uint transactionId)
+        public
+        constant
+        returns (bool)
+    {
+        uint count = 0;
+        for (uint i=0; i<owners.length; i++) {
+            if (confirmations[transactionId][owners[i]])
+                count += 1;
+            if (count == required)
+                return true;
+        }
+    }
+
+    /*
+     * Internal functions
+     */
+    /// @dev Adds a new transaction to the transaction mapping, if transaction does not exist yet.
+    /// @param destination Transaction target address.
+    /// @param value Transaction ether value.
+    /// @param data Transaction data payload.
+    /// @return Returns transaction ID.
+    function addTransaction(address destination, uint value, bytes data)
+        internal
+        notNull(destination)
+        returns (uint transactionId)
+    {
+        transactionId = transactionCount;
+        transactions[transactionId] = Transaction({
+            destination: destination,
+            value: value,
+            data: data,
+            executed: false
+        });
+        transactionCount += 1;
+        Submission(transactionId);
+    }
+
+    /*
+     * Web3 call functions
+     */
+    /// @dev Returns number of confirmations of a transaction.
+    /// @param transactionId Transaction ID.
+    /// @return Number of confirmations.
+    function getConfirmationCount(uint transactionId)
+        public
+        constant
+        returns (uint count)
+    {
+        for (uint i=0; i<owners.length; i++)
+            if (confirmations[transactionId][owners[i]])
+                count += 1;
+    }
+
+    /// @dev Returns total number of transactions after filers are applied.
+    /// @param pending Include pending transactions.
+    /// @param executed Include executed transactions.
+    /// @return Total number of transactions after filters are applied.
+    function getTransactionCount(bool pending, bool executed)
+        public
+        constant
+        returns (uint count)
+    {
+        for (uint i=0; i<transactionCount; i++)
+            if (   pending && !transactions[i].executed
+                || executed && transactions[i].executed)
+                count += 1;
+    }
+
+    /// @dev Returns list of owners.
+    /// @return List of owner addresses.
+    function getOwners()
+        public
+        constant
+        returns (address[])
+    {
+        return owners;
+    }
+
+    /// @dev Returns array with owner addresses, which confirmed transaction.
+    /// @param transactionId Transaction ID.
+    /// @return Returns array of owner addresses.
+    function getConfirmations(uint transactionId)
+        public
+        constant
+        returns (address[] _confirmations)
+    {
+        address[] memory confirmationsTemp = new address[](owners.length);
+        uint count = 0;
+        uint i;
+        for (i=0; i<owners.length; i++)
+            if (confirmations[transactionId][owners[i]]) {
+                confirmationsTemp[count] = owners[i];
+                count += 1;
+            }
+        _confirmations = new address[](count);
+        for (i=0; i<count; i++)
+            _confirmations[i] = confirmationsTemp[i];
+    }
+
+    /// @dev Returns list of transaction IDs in defined range.
+    /// @param from Index start position of transaction array.
+    /// @param to Index end position of transaction array.
+    /// @param pending Include pending transactions.
+    /// @param executed Include executed transactions.
+    /// @return Returns array of transaction IDs.
+    function getTransactionIds(uint from, uint to, bool pending, bool executed)
+        public
+        constant
+        returns (uint[] _transactionIds)
+    {
+        uint[] memory transactionIdsTemp = new uint[](transactionCount);
+        uint count = 0;
+        uint i;
+        for (i=0; i<transactionCount; i++)
+            if (   pending && !transactions[i].executed
+                || executed && transactions[i].executed)
+            {
+                transactionIdsTemp[count] = i;
+                count += 1;
+            }
+        _transactionIds = new uint[](to - from);
+        for (i=from; i<to; i++)
+            _transactionIds[i - from] = transactionIdsTemp[i];
+    }
+}
diff --git a/packages/contracts/src/2.0.0/multisig/MultiSigWalletWithTimeLock.sol b/packages/contracts/src/2.0.0/multisig/MultiSigWalletWithTimeLock.sol
new file mode 100644
index 000000000..9766c2158
--- /dev/null
+++ b/packages/contracts/src/2.0.0/multisig/MultiSigWalletWithTimeLock.sol
@@ -0,0 +1,132 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.10;
+
+import "./MultiSigWallet.sol";
+
+/// @title Multisignature wallet with time lock- Allows multiple parties to execute a transaction after a time lock has passed.
+/// @author Amir Bandeali - <amir@0xProject.com>
+contract MultiSigWalletWithTimeLock is MultiSigWallet {
+
+    event ConfirmationTimeSet(uint indexed transactionId, uint confirmationTime);
+    event TimeLockChange(uint secondsTimeLocked);
+
+    uint public secondsTimeLocked;
+
+    mapping (uint => uint) public confirmationTimes;
+
+    modifier notFullyConfirmed(uint transactionId) {
+        require(!isConfirmed(transactionId));
+        _;
+    }
+
+    modifier fullyConfirmed(uint transactionId) {
+        require(isConfirmed(transactionId));
+        _;
+    }
+
+    modifier pastTimeLock(uint transactionId) {
+        require(block.timestamp >= confirmationTimes[transactionId] + secondsTimeLocked);
+        _;
+    }
+
+    /*
+     * Public functions
+     */
+
+    /// @dev Contract constructor sets initial owners, required number of confirmations, and time lock.
+    /// @param _owners List of initial owners.
+    /// @param _required Number of required confirmations.
+    /// @param _secondsTimeLocked Duration needed after a transaction is confirmed and before it becomes executable, in seconds.
+    function MultiSigWalletWithTimeLock(address[] _owners, uint _required, uint _secondsTimeLocked)
+        public
+        MultiSigWallet(_owners, _required)
+    {
+        secondsTimeLocked = _secondsTimeLocked;
+    }
+
+    /// @dev Changes the duration of the time lock for transactions.
+    /// @param _secondsTimeLocked Duration needed after a transaction is confirmed and before it becomes executable, in seconds.
+    function changeTimeLock(uint _secondsTimeLocked)
+        public
+        onlyWallet
+    {
+        secondsTimeLocked = _secondsTimeLocked;
+        TimeLockChange(_secondsTimeLocked);
+    }
+
+    /// @dev Allows an owner to confirm a transaction.
+    /// @param transactionId Transaction ID.
+    function confirmTransaction(uint transactionId)
+        public
+        ownerExists(msg.sender)
+        transactionExists(transactionId)
+        notConfirmed(transactionId, msg.sender)
+        notFullyConfirmed(transactionId)
+    {
+        confirmations[transactionId][msg.sender] = true;
+        Confirmation(msg.sender, transactionId);
+        if (isConfirmed(transactionId)) {
+            setConfirmationTime(transactionId, block.timestamp);
+        }
+    }
+
+    /// @dev Allows an owner to revoke a confirmation for a transaction.
+    /// @param transactionId Transaction ID.
+    function revokeConfirmation(uint transactionId)
+        public
+        ownerExists(msg.sender)
+        confirmed(transactionId, msg.sender)
+        notExecuted(transactionId)
+        notFullyConfirmed(transactionId)
+    {
+        confirmations[transactionId][msg.sender] = false;
+        Revocation(msg.sender, transactionId);
+    }
+
+    /// @dev Allows anyone to execute a confirmed transaction.
+    /// @param transactionId Transaction ID.
+    function executeTransaction(uint transactionId)
+        public
+        notExecuted(transactionId)
+        fullyConfirmed(transactionId)
+        pastTimeLock(transactionId)
+    {
+        Transaction storage tx = transactions[transactionId];
+        tx.executed = true;
+        if (tx.destination.call.value(tx.value)(tx.data))
+            Execution(transactionId);
+        else {
+            ExecutionFailure(transactionId);
+            tx.executed = false;
+        }
+    }
+
+    /*
+     * Internal functions
+     */
+
+    /// @dev Sets the time of when a submission first passed.
+    function setConfirmationTime(uint transactionId, uint confirmationTime)
+        internal
+    {
+        confirmationTimes[transactionId] = confirmationTime;
+        ConfirmationTimeSet(transactionId, confirmationTime);
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol
new file mode 100644
index 000000000..aed62f54f
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol
@@ -0,0 +1,132 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../utils/LibBytes/LibBytes.sol";
+import "./MixinAuthorizable.sol";
+
+contract ERC20Proxy is
+    MixinAuthorizable
+{
+    // Id of this proxy.
+    bytes4 constant PROXY_ID = bytes4(keccak256("ERC20Token(address)"));
+    
+    function () 
+        external
+    {
+        assembly {
+            // The first 4 bytes of calldata holds the function selector
+            let selector := and(calldataload(0), 0xffffffff00000000000000000000000000000000000000000000000000000000)
+
+            // `transferFrom` will be called with the following parameters:
+            // assetData Encoded byte array.
+            // from Address to transfer asset from.
+            // to Address to transfer asset to.
+            // amount Amount of asset to transfer.
+            // bytes4(keccak256("transferFrom(bytes,address,address,uint256)")) = 0xa85e59e4
+            if eq(selector, 0xa85e59e400000000000000000000000000000000000000000000000000000000) {
+
+                // To lookup a value in a mapping, we load from the storage location keccak256(k, p),
+                // where k is the key left padded to 32 bytes and p is the storage slot
+                let start := mload(64)
+                mstore(start, and(caller, 0xffffffffffffffffffffffffffffffffffffffff))
+                mstore(add(start, 32), authorized_slot)
+
+                // Revert if authorized[msg.sender] == false
+                if iszero(sload(keccak256(start, 64))) {
+                    // Revert with `Error("SENDER_NOT_AUTHORIZED")`
+                    mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                    mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                    mstore(64, 0x0000001553454e4445525f4e4f545f415554484f52495a454400000000000000)
+                    mstore(96, 0)
+                    revert(0, 100)
+                }
+                
+                /////// Token contract address ///////
+                // The token address is found as follows:
+                // * It is stored at offset 4 in `assetData` contents.
+                // * This is stored at offset 32 from `assetData`.
+                // * The offset to `assetData` from Params is stored at offset
+                //   4 in calldata.
+                // * The offset of Params in calldata is 4.
+                // So we read location 4 and add 32 + 4 + 4 to it.
+                let token := calldataload(add(calldataload(4), 40))
+                
+                /////// Setup Header Area ///////
+                // This area holds the 4-byte `transferFrom` selector.
+                // Any trailing data in transferFromSelector will be
+                // overwritten in the next `mstore` call.
+                mstore(0, 0x23b872dd00000000000000000000000000000000000000000000000000000000)
+                
+                /////// Setup Params Area ///////
+                // We copy the fields `from`, `to` and `amount` in bulk
+                // from our own calldata to the new calldata.
+                calldatacopy(4, 36, 96)
+
+                /////// Call `token.transferFrom` using the calldata ///////
+                let success := call(
+                    gas,            // forward all gas
+                    token,          // call address of token contract
+                    0,              // don't send any ETH
+                    0,              // pointer to start of input
+                    100,            // length of input
+                    0,              // write output over input
+                    32              // output size should be 32 bytes
+                )
+
+                /////// Check return data. ///////
+                // If there is no return data, we assume the token incorrectly
+                // does not return a bool. In this case we expect it to revert
+                // on failure, which was handled above.
+                // If the token does return data, we require that it is a single
+                // nonzero 32 bytes value.
+                // So the transfer succeeded if the call succeeded and either
+                // returned nothing, or returned a non-zero 32 byte value. 
+                success := and(success, or(
+                    iszero(returndatasize),
+                    and(
+                        eq(returndatasize, 32),
+                        gt(mload(0), 0)
+                    )
+                ))
+                if success {
+                    return(0, 0)
+                }
+                
+                // Revert with `Error("TRANSFER_FAILED")`
+                mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                mstore(64, 0x0000000f5452414e534645525f4641494c454400000000000000000000000000)
+                mstore(96, 0)
+                revert(0, 100)
+            }
+        }
+    }
+
+    /// @dev Gets the proxy id associated with the proxy address.
+    /// @return Proxy id.
+    function getProxyId()
+        external
+        pure
+        returns (bytes4)
+    {
+        return PROXY_ID;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol
new file mode 100644
index 000000000..b73dc36cc
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol
@@ -0,0 +1,218 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../utils/LibBytes/LibBytes.sol";
+import "./MixinAuthorizable.sol";
+
+contract ERC721Proxy is
+    MixinAuthorizable
+{
+    // Id of this proxy.
+    bytes4 constant PROXY_ID = bytes4(keccak256("ERC721Token(address,uint256,bytes)"));
+
+    function () 
+        external
+    {
+        assembly {
+            // The first 4 bytes of calldata holds the function selector
+            let selector := and(calldataload(0), 0xffffffff00000000000000000000000000000000000000000000000000000000)
+
+            // `transferFrom` will be called with the following parameters:
+            // assetData Encoded byte array.
+            // from Address to transfer asset from.
+            // to Address to transfer asset to.
+            // amount Amount of asset to transfer.
+            // bytes4(keccak256("transferFrom(bytes,address,address,uint256)")) = 0xa85e59e4
+            if eq(selector, 0xa85e59e400000000000000000000000000000000000000000000000000000000) {
+
+                // To lookup a value in a mapping, we load from the storage location keccak256(k, p),
+                // where k is the key left padded to 32 bytes and p is the storage slot
+                let start := mload(64)
+                mstore(start, and(caller, 0xffffffffffffffffffffffffffffffffffffffff))
+                mstore(add(start, 32), authorized_slot)
+
+                // Revert if authorized[msg.sender] == false
+                if iszero(sload(keccak256(start, 64))) {
+                    // Revert with `Error("SENDER_NOT_AUTHORIZED")`
+                    mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                    mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                    mstore(64, 0x0000001553454e4445525f4e4f545f415554484f52495a454400000000000000)
+                    mstore(96, 0)
+                    revert(0, 100)
+                }
+
+                // `transferFrom`.
+                // The function is marked `external`, so no abi decodeding is done for
+                // us. Instead, we expect the `calldata` memory to contain the
+                // following:
+                //
+                // | Area     | Offset | Length  | Contents                            |
+                // |----------|--------|---------|-------------------------------------|
+                // | Header   | 0      | 4       | function selector                   |
+                // | Params   |        | 4 * 32  | function parameters:                |
+                // |          | 4      |         |   1. offset to assetData (*)        |
+                // |          | 36     |         |   2. from                           |
+                // |          | 68     |         |   3. to                             |
+                // |          | 100    |         |   4. amount                         |
+                // | Data     |        |         | assetData:                          |
+                // |          | 132    | 32      | assetData Length                    |
+                // |          | 164    | **      | assetData Contents                  |
+                //
+                // (*): offset is computed from start of function parameters, so offset
+                //      by an additional 4 bytes in the calldata.
+                //
+                // WARNING: The ABIv2 specification allows additional padding between
+                //          the Params and Data section. This will result in a larger
+                //          offset to assetData.
+                
+                // Asset data itself is encoded as follows:
+                //
+                // | Area     | Offset | Length  | Contents                            |
+                // |----------|--------|---------|-------------------------------------|
+                // | Header   | 0      | 4       | function selector                   |
+                // | Params   |        | 3 * 32  | function parameters:                |
+                // |          | 4      | 12 + 20 |   1. token address                  |
+                // |          | 36     |         |   2. tokenId                        |
+                // |          | 68     |         |   3. offset to receiverData (*)     |
+                // | Data     |        |         | receiverData:                       |
+                // |          | 100    | 32      | receiverData Length                 |
+                // |          | 132    | **      | receiverData Contents               |
+                
+                // We construct calldata for the `token.safeTransferFrom` ABI.
+                // The layout of this calldata is in the table below.
+                // 
+                // | Area     | Offset | Length  | Contents                            |
+                // |----------|--------|---------|-------------------------------------|
+                // | Header   | 0      | 4       | function selector                   |
+                // | Params   |        | 4 * 32  | function parameters:                |
+                // |          | 4      |         |   1. from                           |
+                // |          | 36     |         |   2. to                             |
+                // |          | 68     |         |   3. tokenId                        |
+                // |          | 100    |         |   4. offset to receiverData (*)     |
+                // | Data     |        |         | receiverData:                       |
+                // |          | 132    | 32      | receiverData Length                 |
+                // |          | 164    | **      | receiverData Contents               |
+
+                // There exists only 1 of each token.
+                // require(amount == 1, "INVALID_AMOUNT")
+                if sub(calldataload(100), 1) {
+                    // Revert with `Error("INVALID_AMOUNT")`
+                    mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                    mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                    mstore(64, 0x0000000e494e56414c49445f414d4f554e540000000000000000000000000000)
+                    mstore(96, 0)
+                    revert(0, 100)
+                }
+                
+                // Require assetData to be at least 132 bytes
+                let offset := calldataload(4)
+                if lt(calldataload(add(offset, 4)), 132) {
+                    // Revert with `Error("LENGTH_GREATER_THAN_131_REQUIRED")`
+                    mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                    mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                    mstore(64, 0x000000204c454e4754485f475245415445525f5448414e5f3133315f52455155)
+                    mstore(96, 0x4952454400000000000000000000000000000000000000000000000000000000)
+                    revert(0, 100)
+                }
+                
+                /////// Setup State ///////
+                // `cdStart` is the start of the calldata for
+                // `token.safeTransferFrom` (equal to free memory ptr).
+                let cdStart := mload(64)
+                // `dataAreaLength` is the total number of words
+                // needed to store `receiverData`
+                // As-per the ABI spec, this value is padded up to
+                // the nearest multiple of 32,
+                // and includes 32-bytes for length.
+                // It's calculated as folows:
+                //      - Unpadded length in bytes = `mload(receiverData) + 32`
+                //      - Add 31 to convert rounding down to rounding up.
+                //        Combined with the previous and this is `63`.
+                //      - Round down to nearest multiple of 32 by clearing
+                //        bits 0x1F. This is done with `and` and a mask.
+
+                /////// Setup Header Area ///////
+                // This area holds the 4-byte `transferFromSelector`.
+                // Any trailing data in transferFromSelector will be
+                // overwritten in the next `mstore` call.
+                mstore(cdStart, 0xb88d4fde00000000000000000000000000000000000000000000000000000000)
+                
+                /////// Setup Params Area ///////
+                // Each parameter is padded to 32-bytes.
+                // The entire Params Area is 128 bytes.
+                // Notes:
+                //   1. A 20-byte mask is applied to addresses
+                //      to zero-out the unused bytes.
+                //   2. The offset to `receiverData` is the length
+                //      of the Params Area (128 bytes).
+                
+                let length := calldataload(add(offset, 136))
+                let token := calldataload(add(offset, 40))
+                
+                // Round length up to multiple of 32
+                length := and(add(length, 31), 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFE0)
+                
+                // Copy `from` and `to`
+                calldatacopy(add(cdStart, 4), 36, 64)
+                
+                // TokenId
+                mstore(add(cdStart, 68), calldataload(add(offset, 72)))
+                
+                // Offset to receiverData
+                mstore(add(cdStart, 100), 128)
+                
+                // receiverData (including length)
+                calldatacopy(add(cdStart, 132), add(offset, 136), add(length, 32))
+                
+                /////// Call `token.safeTransferFrom` using the calldata ///////
+                let success := call(
+                    gas,                    // forward all gas
+                    token,                  // call address of token contract
+                    0,                      // don't send any ETH
+                    cdStart,                // pointer to start of input
+                    add(length, 164),       // length of input
+                    0,                      // write output to null
+                    0                       // output size is 0 bytes
+                )
+                if success {
+                    return(0, 0)
+                }
+                
+                // Revert with `Error("TRANSFER_FAILED")`
+                mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                mstore(64, 0x0000000f5452414e534645525f4641494c454400000000000000000000000000)
+                mstore(96, 0)
+                revert(0, 100)
+            }
+        }
+    }
+
+    /// @dev Gets the proxy id associated with the proxy address.
+    /// @return Proxy id.
+    function getProxyId()
+        external
+        pure
+        returns (bytes4)
+    {
+        return PROXY_ID;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/MixinAuthorizable.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/MixinAuthorizable.sol
new file mode 100644
index 000000000..3b9584a44
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/MixinAuthorizable.sol
@@ -0,0 +1,118 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../utils/Ownable/Ownable.sol";
+import "./mixins/MAuthorizable.sol";
+
+contract MixinAuthorizable is
+    Ownable,
+    MAuthorizable
+{
+
+    /// @dev Only authorized addresses can invoke functions with this modifier.
+    modifier onlyAuthorized {
+        require(
+            authorized[msg.sender],
+            "SENDER_NOT_AUTHORIZED"
+        );
+        _;
+    }
+
+    mapping (address => bool) public authorized;
+    address[] public authorities;
+
+    /// @dev Authorizes an address.
+    /// @param target Address to authorize.
+    function addAuthorizedAddress(address target)
+        external
+        onlyOwner
+    {
+        require(
+            !authorized[target],
+            "TARGET_ALREADY_AUTHORIZED"
+        );
+
+        authorized[target] = true;
+        authorities.push(target);
+        emit AuthorizedAddressAdded(target, msg.sender);
+    }
+
+    /// @dev Removes authorizion of an address.
+    /// @param target Address to remove authorization from.
+    function removeAuthorizedAddress(address target)
+        external
+        onlyOwner
+    {
+        require(
+            authorized[target],
+            "TARGET_NOT_AUTHORIZED"
+        );
+
+        delete authorized[target];
+        for (uint256 i = 0; i < authorities.length; i++) {
+            if (authorities[i] == target) {
+                authorities[i] = authorities[authorities.length - 1];
+                authorities.length -= 1;
+                break;
+            }
+        }
+        emit AuthorizedAddressRemoved(target, msg.sender);
+    }
+
+    /// @dev Removes authorizion of an address.
+    /// @param target Address to remove authorization from.
+    /// @param index Index of target in authorities array.
+    function removeAuthorizedAddressAtIndex(
+        address target,
+        uint256 index
+    )
+        external
+        onlyOwner
+    {
+        require(
+            authorized[target],
+            "TARGET_NOT_AUTHORIZED"
+        );
+        require(
+            index < authorities.length,
+            "INDEX_OUT_OF_BOUNDS"
+        );
+        require(
+            authorities[index] == target,
+            "AUTHORIZED_ADDRESS_MISMATCH"
+        );
+
+        delete authorized[target];
+        authorities[index] = authorities[authorities.length - 1];
+        authorities.length -= 1;
+        emit AuthorizedAddressRemoved(target, msg.sender);
+    }
+
+    /// @dev Gets all authorized addresses.
+    /// @return Array of authorized addresses.
+    function getAuthorizedAddresses()
+        external
+        view
+        returns (address[] memory)
+    {
+        return authorities;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetData.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetData.sol
new file mode 100644
index 000000000..7ebd6acf0
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetData.sol
@@ -0,0 +1,38 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.23;
+
+// @dev Interface of the asset proxy's assetData.
+// The asset proxies take an ABI encoded `bytes assetData` as argument.
+// This argument is ABI encoded as one of the methods of this interface.
+interface IAssetData {
+    
+    function ERC20Token(address tokenContract)
+        external
+        pure;
+    
+    function ERC721Token(
+        address tokenContract,
+        uint256 tokenId,
+        bytes receiverData
+    )
+        external
+        pure;
+    
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetProxy.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetProxy.sol
new file mode 100644
index 000000000..eacd5a412
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetProxy.sol
@@ -0,0 +1,47 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./IAuthorizable.sol";
+
+contract IAssetProxy is
+    IAuthorizable
+{
+
+    /// @dev Transfers assets. Either succeeds or throws.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param from Address to transfer asset from.
+    /// @param to Address to transfer asset to.
+    /// @param amount Amount of asset to transfer.
+    function transferFrom(
+        bytes assetData,
+        address from,
+        address to,
+        uint256 amount
+    )
+        external;
+    
+    /// @dev Gets the proxy id associated with the proxy address.
+    /// @return Proxy id.
+    function getProxyId()
+        external
+        pure
+        returns (bytes4);
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAuthorizable.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAuthorizable.sol
new file mode 100644
index 000000000..cedd1744c
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAuthorizable.sol
@@ -0,0 +1,53 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../../utils/Ownable/IOwnable.sol";
+
+contract IAuthorizable is
+    IOwnable
+{
+
+    /// @dev Gets all authorized addresses.
+    /// @return Array of authorized addresses.
+    function getAuthorizedAddresses()
+        external
+        view
+        returns (address[]);
+
+    /// @dev Authorizes an address.
+    /// @param target Address to authorize.
+    function addAuthorizedAddress(address target)
+        external;
+
+    /// @dev Removes authorizion of an address.
+    /// @param target Address to remove authorization from.
+    function removeAuthorizedAddress(address target)
+        external;
+
+    /// @dev Removes authorizion of an address.
+    /// @param target Address to remove authorization from.
+    /// @param index Index of target in authorities array.
+    function removeAuthorizedAddressAtIndex(
+        address target,
+        uint256 index
+    )
+        external;
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/libs/LibAssetProxyErrors.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/libs/LibAssetProxyErrors.sol
new file mode 100644
index 000000000..338cb12e2
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/libs/LibAssetProxyErrors.sol
@@ -0,0 +1,36 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+/// @dev This contract documents the revert reasons used in the AssetProxy contracts.
+/// This contract is intended to serve as a reference, but is not actually used for efficiency reasons.
+contract LibAssetProxyErrors {
+
+    /// Authorizable errors ///
+    string constant SENDER_NOT_AUTHORIZED = "SENDER_NOT_AUTHORIZED";                        // Sender not authorized to call this method.
+    string constant TARGET_NOT_AUTHORIZED = "TARGET_NOT_AUTHORIZED";                        // Target address not authorized to call this method.
+    string constant TARGET_ALREADY_AUTHORIZED = "TARGET_ALREADY_AUTHORIZED";                // Target address must not already be authorized.
+    string constant INDEX_OUT_OF_BOUNDS = "INDEX_OUT_OF_BOUNDS";                            // Specified array index is out of bounds.
+    string constant AUTHORIZED_ADDRESS_MISMATCH = "AUTHORIZED_ADDRESS_MISMATCH";            // Address at index does not match given target address.
+
+    /// Transfer errors ///
+    string constant INVALID_AMOUNT = "INVALID_AMOUNT";                                      // Transfer amount must equal 1.
+    string constant TRANSFER_FAILED = "TRANSFER_FAILED";                                    // Transfer failed.
+    string constant LENGTH_GREATER_THAN_131_REQUIRED = "LENGTH_GREATER_THAN_131_REQUIRED";  // Byte array must have a length greater than 0.
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/mixins/MAuthorizable.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/mixins/MAuthorizable.sol
new file mode 100644
index 000000000..6f35bd7ec
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/mixins/MAuthorizable.sol
@@ -0,0 +1,42 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../interfaces/IAuthorizable.sol";
+
+contract MAuthorizable is
+    IAuthorizable
+{
+
+    // Event logged when a new address is authorized.
+    event AuthorizedAddressAdded(
+        address indexed target,
+        address indexed caller
+    );
+
+    // Event logged when a currently authorized address is unauthorized.
+    event AuthorizedAddressRemoved(
+        address indexed target,
+        address indexed caller
+    );
+
+    /// @dev Only authorized addresses can invoke functions with this modifier.
+    modifier onlyAuthorized { revert(); _; }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol b/packages/contracts/src/2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol
new file mode 100644
index 000000000..eb58b3374
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol
@@ -0,0 +1,98 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.10;
+
+import "../../multisig/MultiSigWalletWithTimeLock.sol";
+import "../../utils/LibBytes/LibBytes.sol";
+
+contract AssetProxyOwner is
+    MultiSigWalletWithTimeLock
+{
+    using LibBytes for bytes;
+
+    event AssetProxyRegistration(address assetProxyContract, bool isRegistered);
+
+    // Mapping of AssetProxy contract address =>
+    // if this contract is allowed to call the AssetProxy's `removeAuthorizedAddressAtIndex` method without a time lock.
+    mapping (address => bool) public isAssetProxyRegistered;
+
+    bytes4 constant REMOVE_AUTHORIZED_ADDRESS_AT_INDEX_SELECTOR = bytes4(keccak256("removeAuthorizedAddressAtIndex(address,uint256)"));
+
+    /// @dev Function will revert if the transaction does not call `removeAuthorizedAddressAtIndex`
+    ///      on an approved AssetProxy contract.
+    modifier validRemoveAuthorizedAddressAtIndexTx(uint256 transactionId) {
+        Transaction storage tx = transactions[transactionId];
+        require(isAssetProxyRegistered[tx.destination]);
+        require(tx.data.readBytes4(0) == REMOVE_AUTHORIZED_ADDRESS_AT_INDEX_SELECTOR);
+        _;
+    }
+
+    /// @dev Contract constructor sets initial owners, required number of confirmations,
+    ///      time lock, and list of AssetProxy addresses.
+    /// @param _owners List of initial owners.
+    /// @param _assetProxyContracts Array of AssetProxy contract addresses.
+    /// @param _required Number of required confirmations.
+    /// @param _secondsTimeLocked Duration needed after a transaction is confirmed and before it becomes executable, in seconds.
+    function AssetProxyOwner(
+        address[] memory _owners,
+        address[] memory _assetProxyContracts,
+        uint256 _required,
+        uint256 _secondsTimeLocked
+    )
+        public
+        MultiSigWalletWithTimeLock(_owners, _required, _secondsTimeLocked)
+    {
+        for (uint256 i = 0; i < _assetProxyContracts.length; i++) {
+            address assetProxy = _assetProxyContracts[i];
+            require(assetProxy != address(0));
+            isAssetProxyRegistered[assetProxy] = true;
+        }
+    }
+
+    /// @dev Registers or deregisters an AssetProxy to be able to execute
+    ///      `removeAuthorizedAddressAtIndex` without a timelock.
+    /// @param assetProxyContract Address of AssetProxy contract.
+    /// @param isRegistered Status of approval for AssetProxy contract.
+    function registerAssetProxy(address assetProxyContract, bool isRegistered)
+        public
+        onlyWallet
+        notNull(assetProxyContract)
+    {
+        isAssetProxyRegistered[assetProxyContract] = isRegistered;
+        AssetProxyRegistration(assetProxyContract, isRegistered);
+    }
+
+    /// @dev Allows execution of `removeAuthorizedAddressAtIndex` without time lock.
+    /// @param transactionId Transaction ID.
+    function executeRemoveAuthorizedAddressAtIndex(uint256 transactionId)
+        public
+        notExecuted(transactionId)
+        fullyConfirmed(transactionId)
+        validRemoveAuthorizedAddressAtIndexTx(transactionId)
+    {
+        Transaction storage tx = transactions[transactionId];
+        tx.executed = true;
+        if (tx.destination.call.value(tx.value)(tx.data))
+            Execution(transactionId);
+        else {
+            ExecutionFailure(transactionId);
+            tx.executed = false;
+        }
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/Exchange.sol b/packages/contracts/src/2.0.0/protocol/Exchange/Exchange.sol
new file mode 100644
index 000000000..d36e9633e
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/Exchange.sol
@@ -0,0 +1,52 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./libs/LibConstants.sol";
+import "./MixinExchangeCore.sol";
+import "./MixinSignatureValidator.sol";
+import "./MixinWrapperFunctions.sol";
+import "./MixinAssetProxyDispatcher.sol";
+import "./MixinTransactions.sol";
+import "./MixinMatchOrders.sol";
+
+contract Exchange is
+    MixinExchangeCore,
+    MixinMatchOrders,
+    MixinSignatureValidator,
+    MixinTransactions,
+    MixinAssetProxyDispatcher,
+    MixinWrapperFunctions
+{
+
+    string constant public VERSION = "2.0.1-alpha";
+
+    // Mixins are instantiated in the order they are inherited
+    constructor (bytes memory _zrxAssetData)
+        public
+        LibConstants(_zrxAssetData) // @TODO: Remove when we deploy.
+        MixinExchangeCore()
+        MixinMatchOrders()
+        MixinSignatureValidator()
+        MixinTransactions()
+        MixinAssetProxyDispatcher()
+        MixinWrapperFunctions()
+    {}
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol
new file mode 100644
index 000000000..9e9d88ce7
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol
@@ -0,0 +1,175 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+import "../../utils/Ownable/Ownable.sol";
+import "../../utils/LibBytes/LibBytes.sol";
+import "./mixins/MAssetProxyDispatcher.sol";
+import "../AssetProxy/interfaces/IAssetProxy.sol";
+
+contract MixinAssetProxyDispatcher is
+    Ownable,
+    MAssetProxyDispatcher
+{
+    using LibBytes for bytes;
+    
+    // Mapping from Asset Proxy Id's to their respective Asset Proxy
+    mapping (bytes4 => IAssetProxy) public assetProxies;
+
+    /// @dev Registers an asset proxy to its asset proxy id.
+    ///      Once an asset proxy is registered, it cannot be unregistered.
+    /// @param assetProxy Address of new asset proxy to register.
+    function registerAssetProxy(address assetProxy)
+        external
+        onlyOwner
+    {
+        IAssetProxy assetProxyContract = IAssetProxy(assetProxy);
+
+        // Ensure that no asset proxy exists with current id.
+        bytes4 assetProxyId = assetProxyContract.getProxyId();
+        address currentAssetProxy = assetProxies[assetProxyId];
+        require(
+            currentAssetProxy == address(0),
+            "ASSET_PROXY_ALREADY_EXISTS"
+        );
+
+        // Add asset proxy and log registration.
+        assetProxies[assetProxyId] = assetProxyContract;
+        emit AssetProxyRegistered(
+            assetProxyId,
+            assetProxy
+        );
+    }
+
+    /// @dev Gets an asset proxy.
+    /// @param assetProxyId Id of the asset proxy.
+    /// @return The asset proxy registered to assetProxyId. Returns 0x0 if no proxy is registered.
+    function getAssetProxy(bytes4 assetProxyId)
+        external
+        view
+        returns (address)
+    {
+        return assetProxies[assetProxyId];
+    }
+
+    /// @dev Forwards arguments to assetProxy and calls `transferFrom`. Either succeeds or throws.
+    /// @param assetData Byte array encoded for the asset.
+    /// @param from Address to transfer token from.
+    /// @param to Address to transfer token to.
+    /// @param amount Amount of token to transfer.
+    function dispatchTransferFrom(
+        bytes memory assetData,
+        address from,
+        address to,
+        uint256 amount
+    )
+        internal
+    {
+        // Do nothing if no amount should be transferred.
+        if (amount > 0) {
+            // Ensure assetData length is valid
+            require(
+                assetData.length > 3,
+                "LENGTH_GREATER_THAN_3_REQUIRED"
+            );
+            
+            // Lookup assetProxy
+            bytes4 assetProxyId;
+            assembly {
+                assetProxyId := and(mload(
+                    add(assetData, 32)),
+                    0xFFFFFFFF00000000000000000000000000000000000000000000000000000000
+                )
+            }
+            address assetProxy = assetProxies[assetProxyId];
+
+            // Ensure that assetProxy exists
+            require(
+                assetProxy != address(0),
+                "ASSET_PROXY_DOES_NOT_EXIST"
+            );
+            
+            // We construct calldata for the `assetProxy.transferFrom` ABI.
+            // The layout of this calldata is in the table below.
+            // 
+            // | Area     | Offset | Length  | Contents                                    |
+            // | -------- |--------|---------|-------------------------------------------- |
+            // | Header   | 0      | 4       | function selector                           |
+            // | Params   |        | 4 * 32  | function parameters:                        |
+            // |          | 4      |         |   1. offset to assetData (*)                |
+            // |          | 36     |         |   2. from                                   |
+            // |          | 68     |         |   3. to                                     |
+            // |          | 100    |         |   4. amount                                 |
+            // | Data     |        |         | assetData:                                  |
+            // |          | 132    | 32      | assetData Length                            |
+            // |          | 164    | **      | assetData Contents                          |
+
+            assembly {
+                /////// Setup State ///////
+                // `cdStart` is the start of the calldata for `assetProxy.transferFrom` (equal to free memory ptr).
+                let cdStart := mload(64)
+                // `dataAreaLength` is the total number of words needed to store `assetData`
+                //  As-per the ABI spec, this value is padded up to the nearest multiple of 32,
+                //  and includes 32-bytes for length.
+                let dataAreaLength := and(add(mload(assetData), 63), 0xFFFFFFFFFFFE0)
+                // `cdEnd` is the end of the calldata for `assetProxy.transferFrom`.
+                let cdEnd := add(cdStart, add(132, dataAreaLength))
+
+                
+                /////// Setup Header Area ///////
+                // This area holds the 4-byte `transferFromSelector`.
+                // bytes4(keccak256("transferFrom(bytes,address,address,uint256)")) = 0xa85e59e4
+                mstore(cdStart, 0xa85e59e400000000000000000000000000000000000000000000000000000000)
+                
+                /////// Setup Params Area ///////
+                // Each parameter is padded to 32-bytes. The entire Params Area is 128 bytes.
+                // Notes:
+                //   1. The offset to `assetData` is the length of the Params Area (128 bytes).
+                //   2. A 20-byte mask is applied to addresses to zero-out the unused bytes.
+                mstore(add(cdStart, 4), 128)
+                mstore(add(cdStart, 36), and(from, 0xffffffffffffffffffffffffffffffffffffffff))
+                mstore(add(cdStart, 68), and(to, 0xffffffffffffffffffffffffffffffffffffffff))
+                mstore(add(cdStart, 100), amount)
+                
+                /////// Setup Data Area ///////
+                // This area holds `assetData`.
+                let dataArea := add(cdStart, 132)
+                for {} lt(dataArea, cdEnd) {} {
+                    mstore(dataArea, mload(assetData))
+                    dataArea := add(dataArea, 32)
+                    assetData := add(assetData, 32)
+                }
+
+                /////// Call `assetProxy.transferFrom` using the constructed calldata ///////
+                let success := call(
+                    gas,                    // forward all gas
+                    assetProxy,             // call address of asset proxy
+                    0,                      // don't send any ETH
+                    cdStart,                // pointer to start of input
+                    sub(cdEnd, cdStart),    // length of input  
+                    cdStart,                // write output over input
+                    512                     // reserve 512 bytes for output
+                )
+                if iszero(success) {
+                    revert(cdStart, returndatasize())
+                }
+            }
+        }
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
new file mode 100644
index 000000000..c0ed023ac
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
@@ -0,0 +1,436 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./libs/LibConstants.sol";
+import "./libs/LibFillResults.sol";
+import "./libs/LibOrder.sol";
+import "./libs/LibMath.sol";
+import "./mixins/MExchangeCore.sol";
+import "./mixins/MSignatureValidator.sol";
+import "./mixins/MTransactions.sol";
+import "./mixins/MAssetProxyDispatcher.sol";
+
+contract MixinExchangeCore is
+    LibConstants,
+    LibMath,
+    LibOrder,
+    LibFillResults,
+    MAssetProxyDispatcher,
+    MExchangeCore,
+    MSignatureValidator,
+    MTransactions
+{
+    // Mapping of orderHash => amount of takerAsset already bought by maker
+    mapping (bytes32 => uint256) public filled;
+
+    // Mapping of orderHash => cancelled
+    mapping (bytes32 => bool) public cancelled;
+
+    // Mapping of makerAddress => senderAddress => lowest salt an order can have in order to be fillable
+    // Orders with specified senderAddress and with a salt less than their epoch to are considered cancelled
+    mapping (address => mapping (address => uint256)) public orderEpoch;
+
+    ////// Core exchange functions //////
+
+    /// @dev Cancels all orders created by makerAddress with a salt less than or equal to the targetOrderEpoch
+    ///      and senderAddress equal to msg.sender (or null address if msg.sender == makerAddress).
+    /// @param targetOrderEpoch Orders created with a salt less or equal to this value will be cancelled.
+    function cancelOrdersUpTo(uint256 targetOrderEpoch)
+        external
+    {
+        address makerAddress = getCurrentContextAddress();
+        // If this function is called via `executeTransaction`, we only update the orderEpoch for the makerAddress/msg.sender combination.
+        // This allows external filter contracts to add rules to how orders are cancelled via this function.
+        address senderAddress = makerAddress == msg.sender ? address(0) : msg.sender;
+
+        // orderEpoch is initialized to 0, so to cancelUpTo we need salt + 1
+        uint256 newOrderEpoch = targetOrderEpoch + 1;  
+        uint256 oldOrderEpoch = orderEpoch[makerAddress][senderAddress];
+
+        // Ensure orderEpoch is monotonically increasing
+        require(
+            newOrderEpoch > oldOrderEpoch, 
+            "INVALID_NEW_ORDER_EPOCH"
+        );
+
+        // Update orderEpoch
+        orderEpoch[makerAddress][senderAddress] = newOrderEpoch;
+        emit CancelUpTo(makerAddress, senderAddress, newOrderEpoch);
+    }
+
+    /// @dev Fills the input order.
+    /// @param order Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signature Proof that order has been created by maker.
+    /// @return Amounts filled and fees paid by maker and taker.
+    function fillOrder(
+        Order memory order,
+        uint256 takerAssetFillAmount,
+        bytes memory signature
+    )
+        public
+        returns (FillResults memory fillResults)
+    {
+        // Fetch order info
+        OrderInfo memory orderInfo = getOrderInfo(order);
+
+        // Fetch taker address
+        address takerAddress = getCurrentContextAddress();
+
+        // Get amount of takerAsset to fill
+        uint256 remainingTakerAssetAmount = safeSub(order.takerAssetAmount, orderInfo.orderTakerAssetFilledAmount);
+        uint256 takerAssetFilledAmount = min256(takerAssetFillAmount, remainingTakerAssetAmount);
+
+        // Validate context
+        assertValidFill(
+            order,
+            orderInfo,
+            takerAddress,
+            takerAssetFillAmount,
+            takerAssetFilledAmount,
+            signature
+        );
+
+        // Compute proportional fill amounts
+        fillResults = calculateFillResults(order, takerAssetFilledAmount);
+
+        // Update exchange internal state
+        updateFilledState(
+            order,
+            takerAddress,
+            orderInfo.orderHash,
+            orderInfo.orderTakerAssetFilledAmount,
+            fillResults
+        );
+    
+        // Settle order
+        settleOrder(order, takerAddress, fillResults);
+
+        return fillResults;
+    }
+
+    /// @dev After calling, the order can not be filled anymore.
+    ///      Throws if order is invalid or sender does not have permission to cancel.
+    /// @param order Order to cancel. Order must be OrderStatus.FILLABLE.
+    function cancelOrder(Order memory order)
+        public
+    {
+        // Fetch current order status
+        OrderInfo memory orderInfo = getOrderInfo(order);
+
+        // Validate context
+        assertValidCancel(order, orderInfo);
+
+        // Perform cancel
+        updateCancelledState(order, orderInfo.orderHash);
+    }
+
+    /// @dev Gets information about an order: status, hash, and amount filled.
+    /// @param order Order to gather information on.
+    /// @return OrderInfo Information about the order and its state.
+    ///         See LibOrder.OrderInfo for a complete description.
+    function getOrderInfo(Order memory order)
+        public
+        view
+        returns (OrderInfo memory orderInfo)
+    {
+        // Compute the order hash
+        orderInfo.orderHash = getOrderHash(order);
+
+        // If order.makerAssetAmount is zero, we also reject the order.
+        // While the Exchange contract handles them correctly, they create
+        // edge cases in the supporting infrastructure because they have
+        // an 'infinite' price when computed by a simple division.
+        if (order.makerAssetAmount == 0) {
+            orderInfo.orderStatus = uint8(OrderStatus.INVALID_MAKER_ASSET_AMOUNT);
+            return orderInfo;
+        }
+
+        // If order.takerAssetAmount is zero, then the order will always
+        // be considered filled because 0 == takerAssetAmount == orderTakerAssetFilledAmount
+        // Instead of distinguishing between unfilled and filled zero taker
+        // amount orders, we choose not to support them.
+        if (order.takerAssetAmount == 0) {
+            orderInfo.orderStatus = uint8(OrderStatus.INVALID_TAKER_ASSET_AMOUNT);
+            return orderInfo;
+        }
+
+        // Validate order expiration
+        if (block.timestamp >= order.expirationTimeSeconds) {
+            orderInfo.orderStatus = uint8(OrderStatus.EXPIRED);
+            return orderInfo;
+        }
+
+        // Check if order has been cancelled
+        if (cancelled[orderInfo.orderHash]) {
+            orderInfo.orderStatus = uint8(OrderStatus.CANCELLED);
+            return orderInfo;
+        }
+        if (orderEpoch[order.makerAddress][order.senderAddress] > order.salt) {
+            orderInfo.orderStatus = uint8(OrderStatus.CANCELLED);
+            return orderInfo;
+        }
+
+        // Fetch filled amount and validate order availability
+        orderInfo.orderTakerAssetFilledAmount = filled[orderInfo.orderHash];
+        if (orderInfo.orderTakerAssetFilledAmount >= order.takerAssetAmount) {
+            orderInfo.orderStatus = uint8(OrderStatus.FULLY_FILLED);
+            return orderInfo;
+        }
+
+        // All other statuses are ruled out: order is Fillable
+        orderInfo.orderStatus = uint8(OrderStatus.FILLABLE);
+        return orderInfo;
+    }
+
+    /// @dev Updates state with results of a fill order.
+    /// @param order that was filled.
+    /// @param takerAddress Address of taker who filled the order.
+    /// @param orderTakerAssetFilledAmount Amount of order already filled.
+    /// @return fillResults Amounts filled and fees paid by maker and taker.
+    function updateFilledState(
+        Order memory order,
+        address takerAddress,
+        bytes32 orderHash,
+        uint256 orderTakerAssetFilledAmount,
+        FillResults memory fillResults
+    )
+        internal
+    {
+        // Update state
+        filled[orderHash] = safeAdd(orderTakerAssetFilledAmount, fillResults.takerAssetFilledAmount);
+
+        // Log order
+        emit Fill(
+            order.makerAddress,
+            order.feeRecipientAddress,
+            takerAddress,
+            msg.sender,
+            fillResults.makerAssetFilledAmount,
+            fillResults.takerAssetFilledAmount,
+            fillResults.makerFeePaid,
+            fillResults.takerFeePaid,
+            orderHash,
+            order.makerAssetData,
+            order.takerAssetData
+        );
+    }
+
+    /// @dev Updates state with results of cancelling an order.
+    ///      State is only updated if the order is currently fillable.
+    ///      Otherwise, updating state would have no effect.
+    /// @param order that was cancelled.
+    /// @param orderHash Hash of order that was cancelled.
+    function updateCancelledState(
+        Order memory order,
+        bytes32 orderHash
+    )
+        internal
+    {
+        // Perform cancel
+        cancelled[orderHash] = true;
+
+        // Log cancel
+        emit Cancel(
+            order.makerAddress,
+            order.feeRecipientAddress,
+            msg.sender,
+            orderHash,
+            order.makerAssetData,
+            order.takerAssetData
+        );
+    }
+
+    /// @dev Validates context for fillOrder. Succeeds or throws.
+    /// @param order to be filled.
+    /// @param orderInfo OrderStatus, orderHash, and amount already filled of order.
+    /// @param takerAddress Address of order taker.
+    /// @param takerAssetFillAmount Desired amount of order to fill by taker.
+    /// @param takerAssetFilledAmount Amount of takerAsset that will be filled.
+    /// @param signature Proof that the orders was created by its maker.
+    function assertValidFill(
+        Order memory order,
+        OrderInfo memory orderInfo,
+        address takerAddress,
+        uint256 takerAssetFillAmount,
+        uint256 takerAssetFilledAmount,
+        bytes memory signature
+    )
+        internal
+        view
+    {
+        // An order can only be filled if its status is FILLABLE.
+        require(
+            orderInfo.orderStatus == uint8(OrderStatus.FILLABLE),
+            "ORDER_UNFILLABLE"
+        );
+
+        // Revert if fill amount is invalid
+        require(
+            takerAssetFillAmount != 0,
+            "INVALID_TAKER_AMOUNT"
+        );
+
+        // Validate sender is allowed to fill this order
+        if (order.senderAddress != address(0)) {
+            require(
+                order.senderAddress == msg.sender,
+                "INVALID_SENDER"
+            );
+        }
+
+        // Validate taker is allowed to fill this order
+        if (order.takerAddress != address(0)) {
+            require(
+                order.takerAddress == takerAddress,
+                "INVALID_TAKER"
+            );
+        }
+
+        // Validate Maker signature (check only if first time seen)
+        if (orderInfo.orderTakerAssetFilledAmount == 0) {
+            require(
+                isValidSignature(
+                    orderInfo.orderHash,
+                    order.makerAddress,
+                    signature
+                ),
+                "INVALID_ORDER_SIGNATURE"
+            );
+        }
+
+        // Validate fill order rounding
+        require(
+            !isRoundingError(
+                takerAssetFilledAmount,
+                order.takerAssetAmount,
+                order.makerAssetAmount
+            ),
+            "ROUNDING_ERROR"
+        );
+    }
+
+    /// @dev Validates context for cancelOrder. Succeeds or throws.
+    /// @param order to be cancelled.
+    /// @param orderInfo OrderStatus, orderHash, and amount already filled of order.
+    function assertValidCancel(
+        Order memory order,
+        OrderInfo memory orderInfo
+    )
+        internal
+        view
+    {
+        // Ensure order is valid
+        // An order can only be cancelled if its status is FILLABLE.
+        require(
+            orderInfo.orderStatus == uint8(OrderStatus.FILLABLE),
+            "ORDER_UNFILLABLE"
+        );
+
+        // Validate sender is allowed to cancel this order
+        if (order.senderAddress != address(0)) {
+            require(
+                order.senderAddress == msg.sender,
+                "INVALID_SENDER"
+            );
+        }
+
+        // Validate transaction signed by maker
+        address makerAddress = getCurrentContextAddress();
+        require(
+            order.makerAddress == makerAddress,
+            "INVALID_MAKER"
+        );
+    }
+
+    /// @dev Calculates amounts filled and fees paid by maker and taker.
+    /// @param order to be filled.
+    /// @param takerAssetFilledAmount Amount of takerAsset that will be filled.
+    /// @return fillResults Amounts filled and fees paid by maker and taker.
+    function calculateFillResults(
+        Order memory order,
+        uint256 takerAssetFilledAmount
+    )
+        internal
+        pure
+        returns (FillResults memory fillResults)
+    {
+        // Compute proportional transfer amounts
+        // TODO: All three are multiplied by the same fraction. This can
+        // potentially be optimized.
+        fillResults.takerAssetFilledAmount = takerAssetFilledAmount;
+        fillResults.makerAssetFilledAmount = getPartialAmount(
+            fillResults.takerAssetFilledAmount,
+            order.takerAssetAmount,
+            order.makerAssetAmount
+        );
+        fillResults.makerFeePaid = getPartialAmount(
+            fillResults.takerAssetFilledAmount,
+            order.takerAssetAmount,
+            order.makerFee
+        );
+        fillResults.takerFeePaid = getPartialAmount(
+            fillResults.takerAssetFilledAmount,
+            order.takerAssetAmount,
+            order.takerFee
+        );
+
+        return fillResults;
+    }
+
+   /// @dev Settles an order by transferring assets between counterparties.
+    /// @param order Order struct containing order specifications.
+    /// @param takerAddress Address selling takerAsset and buying makerAsset.
+    /// @param fillResults Amounts to be filled and fees paid by maker and taker.
+    function settleOrder(
+        LibOrder.Order memory order,
+        address takerAddress,
+        LibFillResults.FillResults memory fillResults
+    )
+        private
+    {
+        bytes memory zrxAssetData = ZRX_ASSET_DATA;
+        dispatchTransferFrom(
+            order.makerAssetData,
+            order.makerAddress,
+            takerAddress,
+            fillResults.makerAssetFilledAmount
+        );
+        dispatchTransferFrom(
+            order.takerAssetData,
+            takerAddress,
+            order.makerAddress,
+            fillResults.takerAssetFilledAmount
+        );
+        dispatchTransferFrom(
+            zrxAssetData,
+            order.makerAddress,
+            order.feeRecipientAddress,
+            fillResults.makerFeePaid
+        );
+        dispatchTransferFrom(
+            zrxAssetData,
+            takerAddress,
+            order.feeRecipientAddress,
+            fillResults.takerFeePaid
+        );
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol
new file mode 100644
index 000000000..1a43eec79
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol
@@ -0,0 +1,301 @@
+/*
+  Copyright 2018 ZeroEx Intl.
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./libs/LibConstants.sol";
+import "./libs/LibMath.sol";
+import "./libs/LibOrder.sol";
+import "./libs/LibFillResults.sol";
+import "./mixins/MExchangeCore.sol";
+import "./mixins/MMatchOrders.sol";
+import "./mixins/MTransactions.sol";
+import "./mixins/MAssetProxyDispatcher.sol";
+
+contract MixinMatchOrders is
+    LibConstants,
+    LibMath,
+    MAssetProxyDispatcher,
+    MExchangeCore,
+    MMatchOrders,
+    MTransactions
+{
+    /// @dev Match two complementary orders that have a profitable spread.
+    ///      Each order is filled at their respective price point. However, the calculations are
+    ///      carried out as though the orders are both being filled at the right order's price point.
+    ///      The profit made by the left order goes to the taker (who matched the two orders).
+    /// @param leftOrder First order to match.
+    /// @param rightOrder Second order to match.
+    /// @param leftSignature Proof that order was created by the left maker.
+    /// @param rightSignature Proof that order was created by the right maker.
+    /// @return matchedFillResults Amounts filled and fees paid by maker and taker of matched orders.
+    /// TODO: Make this function external once supported by Solidity (See Solidity Issues #3199, #1603)
+    function matchOrders(
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder,
+        bytes memory leftSignature,
+        bytes memory rightSignature
+    )
+        public
+        returns (LibFillResults.MatchedFillResults memory matchedFillResults)
+    {
+        // We assume that rightOrder.takerAssetData == leftOrder.makerAssetData and rightOrder.makerAssetData == leftOrder.takerAssetData.
+        // If this assumption isn't true, the match will fail at signature validation.
+        rightOrder.makerAssetData = leftOrder.takerAssetData;
+        rightOrder.takerAssetData = leftOrder.makerAssetData;
+
+        // Get left & right order info
+        LibOrder.OrderInfo memory leftOrderInfo = getOrderInfo(leftOrder);
+        LibOrder.OrderInfo memory rightOrderInfo = getOrderInfo(rightOrder);
+
+        // Fetch taker address
+        address takerAddress = getCurrentContextAddress();
+
+        // Either our context is valid or we revert
+        assertValidMatch(leftOrder, rightOrder);
+
+        // Compute proportional fill amounts
+        matchedFillResults = calculateMatchedFillResults(
+            leftOrder,
+            rightOrder,
+            leftOrderInfo.orderTakerAssetFilledAmount,
+            rightOrderInfo.orderTakerAssetFilledAmount
+        );
+
+        // Validate fill contexts
+        assertValidFill(
+            leftOrder,
+            leftOrderInfo,
+            takerAddress,
+            matchedFillResults.left.takerAssetFilledAmount,
+            matchedFillResults.left.takerAssetFilledAmount,
+            leftSignature
+        );
+        assertValidFill(
+            rightOrder,
+            rightOrderInfo,
+            takerAddress,
+            matchedFillResults.right.takerAssetFilledAmount,
+            matchedFillResults.right.takerAssetFilledAmount,
+            rightSignature
+        );
+
+        // Update exchange state
+        updateFilledState(
+            leftOrder,
+            takerAddress,
+            leftOrderInfo.orderHash,
+            leftOrderInfo.orderTakerAssetFilledAmount,
+            matchedFillResults.left
+        );
+        updateFilledState(
+            rightOrder,
+            takerAddress,
+            rightOrderInfo.orderHash,
+            rightOrderInfo.orderTakerAssetFilledAmount,
+            matchedFillResults.right
+        );
+    
+        // Settle matched orders. Succeeds or throws.
+        settleMatchedOrders(
+            leftOrder,
+            rightOrder,
+            takerAddress,
+            matchedFillResults
+        );
+
+        return matchedFillResults;
+    }
+
+    /// @dev Validates context for matchOrders. Succeeds or throws.
+    /// @param leftOrder First order to match.
+    /// @param rightOrder Second order to match.
+    function assertValidMatch(
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder
+    )
+        internal
+        pure
+    {
+        // Make sure there is a profitable spread.
+        // There is a profitable spread iff the cost per unit bought (OrderA.MakerAmount/OrderA.TakerAmount) for each order is greater
+        // than the profit per unit sold of the matched order (OrderB.TakerAmount/OrderB.MakerAmount).
+        // This is satisfied by the equations below:
+        // <leftOrder.makerAssetAmount> / <leftOrder.takerAssetAmount> >= <rightOrder.takerAssetAmount> / <rightOrder.makerAssetAmount>
+        // AND
+        // <rightOrder.makerAssetAmount> / <rightOrder.takerAssetAmount> >= <leftOrder.takerAssetAmount> / <leftOrder.makerAssetAmount>
+        // These equations can be combined to get the following:
+        require(
+            safeMul(leftOrder.makerAssetAmount, rightOrder.makerAssetAmount) >=
+            safeMul(leftOrder.takerAssetAmount, rightOrder.takerAssetAmount),
+            "NEGATIVE_SPREAD_REQUIRED"
+        );
+    }
+
+    /// @dev Calculates fill amounts for the matched orders.
+    ///      Each order is filled at their respective price point. However, the calculations are
+    ///      carried out as though the orders are both being filled at the right order's price point.
+    ///      The profit made by the leftOrder order goes to the taker (who matched the two orders).
+    /// @param leftOrder First order to match.
+    /// @param rightOrder Second order to match.
+    /// @param leftOrderTakerAssetFilledAmount Amount of left order already filled.
+    /// @param rightOrderTakerAssetFilledAmount Amount of right order already filled.
+    /// @param matchedFillResults Amounts to fill and fees to pay by maker and taker of matched orders.
+    function calculateMatchedFillResults(
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder,
+        uint256 leftOrderTakerAssetFilledAmount,
+        uint256 rightOrderTakerAssetFilledAmount
+    )
+        internal
+        pure
+        returns (LibFillResults.MatchedFillResults memory matchedFillResults)
+    {
+        // We settle orders at the exchange rate of the right order.
+        // The amount saved by the left maker goes to the taker.
+        // Either the left or right order will be fully filled; possibly both.
+        // The left order is fully filled iff the right order can sell more than left can buy.
+        // That is: the amount required to fill the left order is less than or equal to
+        //          the amount we can spend from the right order:
+        //          <leftTakerAssetAmountRemaining> <= <rightTakerAssetAmountRemaining> * <rightMakerToTakerRatio>
+        //          <leftTakerAssetAmountRemaining> <= <rightTakerAssetAmountRemaining> * <rightOrder.makerAssetAmount> / <rightOrder.takerAssetAmount>
+        //          <leftTakerAssetAmountRemaining> * <rightOrder.takerAssetAmount> <= <rightTakerAssetAmountRemaining> * <rightOrder.makerAssetAmount>
+        uint256 leftTakerAssetAmountRemaining = safeSub(leftOrder.takerAssetAmount, leftOrderTakerAssetFilledAmount);
+        uint256 rightTakerAssetAmountRemaining = safeSub(rightOrder.takerAssetAmount, rightOrderTakerAssetFilledAmount);
+        uint256 leftTakerAssetFilledAmount;
+        uint256 rightTakerAssetFilledAmount;
+        if (
+            safeMul(leftTakerAssetAmountRemaining, rightOrder.takerAssetAmount) <=
+            safeMul(rightTakerAssetAmountRemaining, rightOrder.makerAssetAmount)
+        ) {
+            // Left order will be fully filled: maximally fill left
+            leftTakerAssetFilledAmount = leftTakerAssetAmountRemaining;
+
+            // The right order receives an amount proportional to how much was spent.
+            // TODO: Can we ensure rounding error is in the correct direction?
+            rightTakerAssetFilledAmount = getPartialAmount(
+                rightOrder.takerAssetAmount,
+                rightOrder.makerAssetAmount,
+                leftTakerAssetFilledAmount
+            );
+        } else {
+            // Right order will be fully filled: maximally fill right
+            rightTakerAssetFilledAmount = rightTakerAssetAmountRemaining;
+
+            // The left order receives an amount proportional to how much was spent.
+            // TODO: Can we ensure rounding error is in the correct direction?
+            leftTakerAssetFilledAmount = getPartialAmount(
+                rightOrder.makerAssetAmount,
+                rightOrder.takerAssetAmount,
+                rightTakerAssetFilledAmount
+            );
+        }
+
+        // Calculate fill results for left order
+        matchedFillResults.left = calculateFillResults(
+            leftOrder,
+            leftTakerAssetFilledAmount
+        );
+
+        // Calculate fill results for right order
+        matchedFillResults.right = calculateFillResults(
+            rightOrder,
+            rightTakerAssetFilledAmount
+        );
+
+        // Calculate amount given to taker
+        matchedFillResults.leftMakerAssetSpreadAmount = safeSub(
+            matchedFillResults.left.makerAssetFilledAmount,
+            matchedFillResults.right.takerAssetFilledAmount
+        );
+
+        // Return fill results
+        return matchedFillResults;
+    }
+
+    /// @dev Settles matched order by transferring appropriate funds between order makers, taker, and fee recipient.
+    /// @param leftOrder First matched order.
+    /// @param rightOrder Second matched order.
+    /// @param takerAddress Address that matched the orders. The taker receives the spread between orders as profit.
+    /// @param matchedFillResults Struct holding amounts to transfer between makers, taker, and fee recipients.
+    function settleMatchedOrders(
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder,
+        address takerAddress,
+        LibFillResults.MatchedFillResults memory matchedFillResults
+    )
+        private
+    {
+        bytes memory zrxAssetData = ZRX_ASSET_DATA;
+        // Order makers and taker
+        dispatchTransferFrom(
+            leftOrder.makerAssetData,
+            leftOrder.makerAddress,
+            rightOrder.makerAddress,
+            matchedFillResults.right.takerAssetFilledAmount
+        );
+        dispatchTransferFrom(
+            rightOrder.makerAssetData,
+            rightOrder.makerAddress,
+            leftOrder.makerAddress,
+            matchedFillResults.left.takerAssetFilledAmount
+        );
+        dispatchTransferFrom(
+            leftOrder.makerAssetData,
+            leftOrder.makerAddress,
+            takerAddress,
+            matchedFillResults.leftMakerAssetSpreadAmount
+        );
+
+        // Maker fees
+        dispatchTransferFrom(
+            zrxAssetData,
+            leftOrder.makerAddress,
+            leftOrder.feeRecipientAddress,
+            matchedFillResults.left.makerFeePaid
+        );
+        dispatchTransferFrom(
+            zrxAssetData,
+            rightOrder.makerAddress,
+            rightOrder.feeRecipientAddress,
+            matchedFillResults.right.makerFeePaid
+        );
+
+        // Taker fees
+        if (leftOrder.feeRecipientAddress == rightOrder.feeRecipientAddress) {
+            dispatchTransferFrom(
+                zrxAssetData,
+                takerAddress,
+                leftOrder.feeRecipientAddress,
+                safeAdd(
+                    matchedFillResults.left.takerFeePaid,
+                    matchedFillResults.right.takerFeePaid
+                )
+            );
+        } else {
+            dispatchTransferFrom(
+                zrxAssetData,
+                takerAddress,
+                leftOrder.feeRecipientAddress,
+                matchedFillResults.left.takerFeePaid
+            );
+            dispatchTransferFrom(
+                zrxAssetData,
+                takerAddress,
+                rightOrder.feeRecipientAddress,
+                matchedFillResults.right.takerFeePaid
+            );
+        }
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol
new file mode 100644
index 000000000..29172057a
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol
@@ -0,0 +1,255 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+import "../../utils/LibBytes/LibBytes.sol";
+import "./mixins/MSignatureValidator.sol";
+import "./mixins/MTransactions.sol";
+import "./interfaces/IWallet.sol";
+import "./interfaces/IValidator.sol";
+
+contract MixinSignatureValidator is
+    MSignatureValidator,
+    MTransactions
+{
+    using LibBytes for bytes;
+    
+    // Mapping of hash => signer => signed
+    mapping (bytes32 => mapping (address => bool)) public preSigned;
+
+    // Mapping of signer => validator => approved
+    mapping (address => mapping (address => bool)) public allowedValidators;
+
+    /// @dev Approves a hash on-chain using any valid signature type.
+    ///      After presigning a hash, the preSign signature type will become valid for that hash and signer.
+    /// @param signerAddress Address that should have signed the given hash.
+    /// @param signature Proof that the hash has been signed by signer.
+    function preSign(
+        bytes32 hash,
+        address signerAddress,
+        bytes signature
+    )
+        external
+    {
+        require(
+            isValidSignature(
+                hash,
+                signerAddress,
+                signature
+            ),
+            "INVALID_SIGNATURE"
+        );
+        preSigned[hash][signerAddress] = true;
+    }
+
+    /// @dev Approves/unnapproves a Validator contract to verify signatures on signer's behalf.
+    /// @param validatorAddress Address of Validator contract.
+    /// @param approval Approval or disapproval of  Validator contract.
+    function setSignatureValidatorApproval(
+        address validatorAddress,
+        bool approval
+    )
+        external
+    {
+        address signerAddress = getCurrentContextAddress();
+        allowedValidators[signerAddress][validatorAddress] = approval;
+        emit SignatureValidatorApproval(
+            signerAddress,
+            validatorAddress,
+            approval
+        );
+    }
+
+    /// @dev Verifies that a hash has been signed by the given signer.
+    /// @param hash Any 32 byte hash.
+    /// @param signerAddress Address that should have signed the given hash.
+    /// @param signature Proof that the hash has been signed by signer.
+    /// @return True if the address recovered from the provided signature matches the input signer address.
+    function isValidSignature(
+        bytes32 hash,
+        address signerAddress,
+        bytes memory signature
+    )
+        public
+        view
+        returns (bool isValid)
+    {
+        // TODO: Domain separation: make hash depend on role. (Taker sig should not be valid as maker sig, etc.)
+        require(
+            signature.length > 0,
+            "LENGTH_GREATER_THAN_0_REQUIRED"
+        );
+
+        // Ensure signature is supported
+        uint8 signatureTypeRaw = uint8(signature.popLastByte());
+        require(
+            signatureTypeRaw < uint8(SignatureType.NSignatureTypes),
+            "SIGNATURE_UNSUPPORTED"
+        );
+
+        // Pop last byte off of signature byte array.
+        SignatureType signatureType = SignatureType(signatureTypeRaw);
+
+        // Variables are not scoped in Solidity.
+        uint8 v;
+        bytes32 r;
+        bytes32 s;
+        address recovered;
+
+        // Always illegal signature.
+        // This is always an implicit option since a signer can create a
+        // signature array with invalid type or length. We may as well make
+        // it an explicit option. This aids testing and analysis. It is
+        // also the initialization value for the enum type.
+        if (signatureType == SignatureType.Illegal) {
+            revert("SIGNATURE_ILLEGAL");
+
+        // Always invalid signature.
+        // Like Illegal, this is always implicitly available and therefore
+        // offered explicitly. It can be implicitly created by providing
+        // a correctly formatted but incorrect signature.
+        } else if (signatureType == SignatureType.Invalid) {
+            require(
+                signature.length == 0,
+                "LENGTH_0_REQUIRED"
+            );
+            isValid = false;
+            return isValid;
+
+        // Signature using EIP712
+        } else if (signatureType == SignatureType.EIP712) {
+            require(
+                signature.length == 65,
+                "LENGTH_65_REQUIRED"
+            );
+            v = uint8(signature[0]);
+            r = signature.readBytes32(1);
+            s = signature.readBytes32(33);
+            recovered = ecrecover(hash, v, r, s);
+            isValid = signerAddress == recovered;
+            return isValid;
+
+        // Signed using web3.eth_sign
+        } else if (signatureType == SignatureType.EthSign) {
+            require(
+                signature.length == 65,
+                "LENGTH_65_REQUIRED"
+            );
+            v = uint8(signature[0]);
+            r = signature.readBytes32(1);
+            s = signature.readBytes32(33);
+            recovered = ecrecover(
+                keccak256(abi.encodePacked(
+                    "\x19Ethereum Signed Message:\n32",
+                    hash
+                )),
+                v,
+                r,
+                s
+            );
+            isValid = signerAddress == recovered;
+            return isValid;
+
+        // Implicitly signed by caller.
+        // The signer has initiated the call. In the case of non-contract
+        // accounts it means the transaction itself was signed.
+        // Example: let's say for a particular operation three signatures
+        // A, B and C are required. To submit the transaction, A and B can
+        // give a signature to C, who can then submit the transaction using
+        // `Caller` for his own signature. Or A and C can sign and B can
+        // submit using `Caller`. Having `Caller` allows this flexibility.
+        } else if (signatureType == SignatureType.Caller) {
+            require(
+                signature.length == 0,
+                "LENGTH_0_REQUIRED"
+            );
+            isValid = signerAddress == msg.sender;
+            return isValid;
+
+        // Signature verified by wallet contract.
+        // If used with an order, the maker of the order is the wallet contract.
+        } else if (signatureType == SignatureType.Wallet) {
+            isValid = IWallet(signerAddress).isValidSignature(hash, signature);
+            return isValid;
+
+        // Signature verified by validator contract.
+        // If used with an order, the maker of the order can still be an EOA.
+        // A signature using this type should be encoded as:
+        // | Offset   | Length | Contents                        |
+        // | 0x00     | x      | Signature to validate           |
+        // | 0x00 + x | 20     | Address of validator contract   |
+        // | 0x14 + x | 1      | Signature type is always "\x06" |
+        } else if (signatureType == SignatureType.Validator) {
+            // Pop last 20 bytes off of signature byte array.
+
+            address validatorAddress = signature.popLast20Bytes();
+            
+            // Ensure signer has approved validator.
+            if (!allowedValidators[signerAddress][validatorAddress]) {
+                return false;
+            }
+            isValid = IValidator(validatorAddress).isValidSignature(
+                hash,
+                signerAddress,
+                signature
+            );
+            return isValid;
+
+        // Signer signed hash previously using the preSign function.
+        } else if (signatureType == SignatureType.PreSigned) {
+            isValid = preSigned[hash][signerAddress];
+            return isValid;
+
+        // Signature from Trezor hardware wallet.
+        // It differs from web3.eth_sign in the encoding of message length
+        // (Bitcoin varint encoding vs ascii-decimal, the latter is not
+        // self-terminating which leads to ambiguities).
+        // See also:
+        // https://en.bitcoin.it/wiki/Protocol_documentation#Variable_length_integer
+        // https://github.com/trezor/trezor-mcu/blob/master/firmware/ethereum.c#L602
+        // https://github.com/trezor/trezor-mcu/blob/master/firmware/crypto.c#L36
+        } else if (signatureType == SignatureType.Trezor) {
+            require(
+                signature.length == 65,
+                "LENGTH_65_REQUIRED"
+            );
+            v = uint8(signature[0]);
+            r = signature.readBytes32(1);
+            s = signature.readBytes32(33);
+            recovered = ecrecover(
+                keccak256(abi.encodePacked(
+                    "\x19Ethereum Signed Message:\n\x20",
+                    hash
+                )),
+                v,
+                r,
+                s
+            );
+            isValid = signerAddress == recovered;
+            return isValid;
+        }
+
+        // Anything else is illegal (We do not return false because
+        // the signature may actually be valid, just not in a format
+        // that we currently support. In this case returning false
+        // may lead the caller to incorrectly believe that the
+        // signature was invalid.)
+        revert("SIGNATURE_UNSUPPORTED");
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol
new file mode 100644
index 000000000..31f7f2847
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol
@@ -0,0 +1,154 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+pragma solidity ^0.4.24;
+
+import "./libs/LibExchangeErrors.sol";
+import "./mixins/MSignatureValidator.sol";
+import "./mixins/MTransactions.sol";
+import "./libs/LibEIP712.sol";
+
+contract MixinTransactions is
+    LibEIP712,
+    MSignatureValidator,
+    MTransactions
+{
+
+    // Mapping of transaction hash => executed
+    // This prevents transactions from being executed more than once.
+    mapping (bytes32 => bool) public transactions;
+
+    // Address of current transaction signer
+    address public currentContextAddress;
+
+    // Hash for the EIP712 ZeroEx Transaction Schema
+    bytes32 constant EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH = keccak256(abi.encodePacked(
+        "ZeroExTransaction(",
+        "uint256 salt,",
+        "address signerAddress,",
+        "bytes data",
+        ")"
+    ));
+
+    /// @dev Calculates EIP712 hash of the Transaction.
+    /// @param salt Arbitrary number to ensure uniqueness of transaction hash.
+    /// @param signerAddress Address of transaction signer.
+    /// @param data AbiV2 encoded calldata.
+    /// @return EIP712 hash of the Transaction.
+    function hashZeroExTransaction(
+        uint256 salt,
+        address signerAddress,
+        bytes memory data
+    )
+        internal
+        pure
+        returns (bytes32 result)
+    {
+        bytes32 schemaHash = EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH;
+        bytes32 dataHash = keccak256(data);
+        // Assembly for more efficiently computing:
+        // keccak256(abi.encode(
+        //   EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH,
+        //   salt,
+        //   signerAddress,
+        //   keccak256(data)
+        //  ));
+        assembly {
+            let memPtr := mload(64)
+            mstore(memPtr, schemaHash)
+            mstore(add(memPtr, 32), salt)
+            mstore(add(memPtr, 64), and(signerAddress, 0xffffffffffffffffffffffffffffffffffffffff))
+            mstore(add(memPtr, 96), dataHash)
+            result := keccak256(memPtr, 128)
+        }
+
+        return result;
+    }
+
+    /// @dev Executes an exchange method call in the context of signer.
+    /// @param salt Arbitrary number to ensure uniqueness of transaction hash.
+    /// @param signerAddress Address of transaction signer.
+    /// @param data AbiV2 encoded calldata.
+    /// @param signature Proof of signer transaction by signer.
+    function executeTransaction(
+        uint256 salt,
+        address signerAddress,
+        bytes data,
+        bytes signature
+    )
+        external
+    {
+        // Prevent reentrancy
+        require(
+            currentContextAddress == address(0),
+            "REENTRANCY_ILLEGAL"
+        );
+
+        bytes32 transactionHash = hashEIP712Message(hashZeroExTransaction(
+            salt,
+            signerAddress,
+            data
+        ));
+
+        // Validate transaction has not been executed
+        require(
+            !transactions[transactionHash],
+            "INVALID_TX_HASH"
+        );
+
+        // Transaction always valid if signer is sender of transaction
+        if (signerAddress != msg.sender) {
+            // Validate signature
+            require(
+                isValidSignature(
+                    transactionHash,
+                    signerAddress,
+                    signature
+                ),
+                "INVALID_TX_SIGNATURE"
+            );
+
+            // Set the current transaction signer
+            currentContextAddress = signerAddress;
+        }
+
+        // Execute transaction
+        transactions[transactionHash] = true;
+        require(
+            address(this).delegatecall(data),
+            "FAILED_EXECUTION"
+        );
+
+        // Reset current transaction signer
+        // TODO: Check if gas is paid when currentContextAddress is already 0.
+        currentContextAddress = address(0);
+    }
+
+    /// @dev The current function will be called in the context of this address (either 0x transaction signer or `msg.sender`).
+    ///      If calling a fill function, this address will represent the taker.
+    ///      If calling a cancel function, this address will represent the maker.
+    /// @return Signer of 0x transaction if entry point is `executeTransaction`.
+    ///         `msg.sender` if entry point is any other function.
+    function getCurrentContextAddress()
+        internal
+        view
+        returns (address)
+    {
+        address contextAddress = currentContextAddress == address(0) ? msg.sender : currentContextAddress;
+        return contextAddress;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinWrapperFunctions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinWrapperFunctions.sol
new file mode 100644
index 000000000..00668ca43
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinWrapperFunctions.sol
@@ -0,0 +1,531 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./libs/LibMath.sol";
+import "./libs/LibOrder.sol";
+import "./libs/LibFillResults.sol";
+import "./mixins/MExchangeCore.sol";
+
+contract MixinWrapperFunctions is
+    LibMath,
+    LibFillResults,
+    MExchangeCore
+{
+    /// @dev Fills the input order. Reverts if exact takerAssetFillAmount not filled.
+    /// @param order Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signature Proof that order has been created by maker.
+    function fillOrKillOrder(
+        LibOrder.Order memory order,
+        uint256 takerAssetFillAmount,
+        bytes memory signature
+    )
+        public
+        returns (FillResults memory fillResults)
+    {
+        fillResults = fillOrder(
+            order,
+            takerAssetFillAmount,
+            signature
+        );
+        require(
+            fillResults.takerAssetFilledAmount == takerAssetFillAmount,
+            "COMPLETE_FILL_FAILED"
+        );
+        return fillResults;
+    }
+
+    /// @dev Fills an order with specified parameters and ECDSA signature.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param order Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signature Proof that order has been created by maker.
+    /// @return Amounts filled and fees paid by maker and taker.
+    function fillOrderNoThrow(
+        LibOrder.Order memory order,
+        uint256 takerAssetFillAmount,
+        bytes memory signature
+    )
+        public
+        returns (FillResults memory fillResults)
+    {
+        // We need to call MExchangeCore.fillOrder using a delegatecall in
+        // assembly so that we can intercept a call that throws. For this, we
+        // need the input encoded in memory in the Ethereum ABIv2 format [1].
+
+        // | Area     | Offset | Length  | Contents                                    |
+        // | -------- |--------|---------|-------------------------------------------- |
+        // | Header   | 0x00   | 4       | function selector                           |
+        // | Params   |        | 3 * 32  | function parameters:                        |
+        // |          | 0x00   |         |   1. offset to order (*)                    |
+        // |          | 0x20   |         |   2. takerAssetFillAmount                   |
+        // |          | 0x40   |         |   3. offset to signature (*)                |
+        // | Data     |        | 12 * 32 | order:                                      |
+        // |          | 0x000  |         |   1.  senderAddress                         |
+        // |          | 0x020  |         |   2.  makerAddress                          |
+        // |          | 0x040  |         |   3.  takerAddress                          |
+        // |          | 0x060  |         |   4.  feeRecipientAddress                   |
+        // |          | 0x080  |         |   5.  makerAssetAmount                      |
+        // |          | 0x0A0  |         |   6.  takerAssetAmount                      |
+        // |          | 0x0C0  |         |   7.  makerFeeAmount                        |
+        // |          | 0x0E0  |         |   8.  takerFeeAmount                        |
+        // |          | 0x100  |         |   9.  expirationTimeSeconds                 |
+        // |          | 0x120  |         |   10. salt                                  |
+        // |          | 0x140  |         |   11. Offset to makerAssetData (*)          |
+        // |          | 0x160  |         |   12. Offset to takerAssetData (*)          |
+        // |          | 0x180  | 32      | makerAssetData Length                       |
+        // |          | 0x1A0  | **      | makerAssetData Contents                     |
+        // |          | 0x1C0  | 32      | takerAssetData Length                       |
+        // |          | 0x1E0  | **      | takerAssetData Contents                     |
+        // |          | 0x200  | 32      | signature Length                            |
+        // |          | 0x220  | **      | signature Contents                          |
+
+        // * Offsets are calculated from the beginning of the current area: Header, Params, Data:
+        //     An offset stored in the Params area is calculated from the beginning of the Params section.
+        //     An offset stored in the Data area is calculated from the beginning of the Data section.
+
+        // ** The length of dynamic array contents are stored in the field immediately preceeding the contents.
+
+        // [1]: https://solidity.readthedocs.io/en/develop/abi-spec.html
+
+        bytes4 fillOrderSelector = this.fillOrder.selector;
+
+        assembly {
+
+            // Areas below may use the following variables:
+            //   1. <area>Start   -- Start of this area in memory
+            //   2. <area>End     -- End of this area in memory. This value may
+            //                       be precomputed (before writing contents),
+            //                       or it may be computed as contents are written.
+            //   3. <area>Offset  -- Current offset into area. If an area's End
+            //                       is precomputed, this variable tracks the
+            //                       offsets of contents as they are written.
+
+            /////// Setup Header Area ///////
+            // Load free memory pointer
+            let headerAreaStart := mload(0x40)
+            mstore(headerAreaStart, fillOrderSelector)
+            let headerAreaEnd := add(headerAreaStart, 0x4)
+
+            /////// Setup Params Area ///////
+            // This area is preallocated and written to later.
+            // This is because we need to fill in offsets that have not yet been calculated.
+            let paramsAreaStart := headerAreaEnd
+            let paramsAreaEnd := add(paramsAreaStart, 0x60)
+            let paramsAreaOffset := paramsAreaStart
+
+            /////// Setup Data Area ///////
+            let dataAreaStart := paramsAreaEnd
+            let dataAreaEnd := dataAreaStart
+
+            // Offset from the source data we're reading from
+            let sourceOffset := order
+            // arrayLenBytes and arrayLenWords track the length of a dynamically-allocated bytes array.
+            let arrayLenBytes := 0
+            let arrayLenWords := 0
+
+            /////// Write order Struct ///////
+            // Write memory location of Order, relative to the start of the
+            // parameter list, then increment the paramsAreaOffset respectively.
+            mstore(paramsAreaOffset, sub(dataAreaEnd, paramsAreaStart))
+            paramsAreaOffset := add(paramsAreaOffset, 0x20)
+
+            // Write values for each field in the order
+            // It would be nice to use a loop, but we save on gas by writing
+            // the stores sequentially.
+            mstore(dataAreaEnd, mload(sourceOffset))                            // makerAddress
+            mstore(add(dataAreaEnd, 0x20), mload(add(sourceOffset, 0x20)))      // takerAddress
+            mstore(add(dataAreaEnd, 0x40), mload(add(sourceOffset, 0x40)))      // feeRecipientAddress
+            mstore(add(dataAreaEnd, 0x60), mload(add(sourceOffset, 0x60)))      // senderAddress
+            mstore(add(dataAreaEnd, 0x80), mload(add(sourceOffset, 0x80)))      // makerAssetAmount
+            mstore(add(dataAreaEnd, 0xA0), mload(add(sourceOffset, 0xA0)))      // takerAssetAmount
+            mstore(add(dataAreaEnd, 0xC0), mload(add(sourceOffset, 0xC0)))      // makerFeeAmount
+            mstore(add(dataAreaEnd, 0xE0), mload(add(sourceOffset, 0xE0)))      // takerFeeAmount
+            mstore(add(dataAreaEnd, 0x100), mload(add(sourceOffset, 0x100)))    // expirationTimeSeconds
+            mstore(add(dataAreaEnd, 0x120), mload(add(sourceOffset, 0x120)))    // salt
+            mstore(add(dataAreaEnd, 0x140), mload(add(sourceOffset, 0x140)))    // Offset to makerAssetData
+            mstore(add(dataAreaEnd, 0x160), mload(add(sourceOffset, 0x160)))    // Offset to takerAssetData
+            dataAreaEnd := add(dataAreaEnd, 0x180)
+            sourceOffset := add(sourceOffset, 0x180)
+
+            // Write offset to <order.makerAssetData>
+            mstore(add(dataAreaStart, mul(10, 0x20)), sub(dataAreaEnd, dataAreaStart))
+
+            // Calculate length of <order.makerAssetData>
+            sourceOffset := mload(add(order, 0x140)) // makerAssetData
+            arrayLenBytes := mload(sourceOffset)
+            sourceOffset := add(sourceOffset, 0x20)
+            arrayLenWords := div(add(arrayLenBytes, 0x1F), 0x20)
+
+            // Write length of <order.makerAssetData>
+            mstore(dataAreaEnd, arrayLenBytes)
+            dataAreaEnd := add(dataAreaEnd, 0x20)
+
+            // Write contents of <order.makerAssetData>
+            for {let i := 0} lt(i, arrayLenWords) {i := add(i, 1)} {
+                mstore(dataAreaEnd, mload(sourceOffset))
+                dataAreaEnd := add(dataAreaEnd, 0x20)
+                sourceOffset := add(sourceOffset, 0x20)
+            }
+
+            // Write offset to <order.takerAssetData>
+            mstore(add(dataAreaStart, mul(11, 0x20)), sub(dataAreaEnd, dataAreaStart))
+
+            // Calculate length of <order.takerAssetData>
+            sourceOffset := mload(add(order, 0x160)) // takerAssetData
+            arrayLenBytes := mload(sourceOffset)
+            sourceOffset := add(sourceOffset, 0x20)
+            arrayLenWords := div(add(arrayLenBytes, 0x1F), 0x20)
+
+            // Write length of <order.takerAssetData>
+            mstore(dataAreaEnd, arrayLenBytes)
+            dataAreaEnd := add(dataAreaEnd, 0x20)
+
+            // Write contents of  <order.takerAssetData>
+            for {let i := 0} lt(i, arrayLenWords) {i := add(i, 1)} {
+                mstore(dataAreaEnd, mload(sourceOffset))
+                dataAreaEnd := add(dataAreaEnd, 0x20)
+                sourceOffset := add(sourceOffset, 0x20)
+            }
+
+            /////// Write takerAssetFillAmount ///////
+            mstore(paramsAreaOffset, takerAssetFillAmount)
+            paramsAreaOffset := add(paramsAreaOffset, 0x20)
+
+            /////// Write signature ///////
+            // Write offset to paramsArea
+            mstore(paramsAreaOffset, sub(dataAreaEnd, paramsAreaStart))
+
+            // Calculate length of signature
+            sourceOffset := signature
+            arrayLenBytes := mload(sourceOffset)
+            sourceOffset := add(sourceOffset, 0x20)
+            arrayLenWords := div(add(arrayLenBytes, 0x1F), 0x20)
+
+            // Write length of signature
+            mstore(dataAreaEnd, arrayLenBytes)
+            dataAreaEnd := add(dataAreaEnd, 0x20)
+
+            // Write contents of signature
+            for {let i := 0} lt(i, arrayLenWords) {i := add(i, 1)} {
+                mstore(dataAreaEnd, mload(sourceOffset))
+                dataAreaEnd := add(dataAreaEnd, 0x20)
+                sourceOffset := add(sourceOffset, 0x20)
+            }
+
+            // Execute delegatecall
+            let success := delegatecall(
+                gas,                                // forward all gas, TODO: look into gas consumption of assert/throw
+                address,                            // call address of this contract
+                headerAreaStart,                    // pointer to start of input
+                sub(dataAreaEnd, headerAreaStart),  // length of input
+                headerAreaStart,                    // write output over input
+                128                                 // output size is 128 bytes
+            )
+            switch success
+            case 0 {
+                mstore(fillResults, 0)
+                mstore(add(fillResults, 32), 0)
+                mstore(add(fillResults, 64), 0)
+                mstore(add(fillResults, 96), 0)
+            }
+            case 1 {
+                mstore(fillResults, mload(headerAreaStart))
+                mstore(add(fillResults, 32), mload(add(headerAreaStart, 32)))
+                mstore(add(fillResults, 64), mload(add(headerAreaStart, 64)))
+                mstore(add(fillResults, 96), mload(add(headerAreaStart, 96)))
+            }
+        }
+        return fillResults;
+    }
+
+    /// @dev Synchronously executes multiple calls of fillOrder.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmounts Array of desired amounts of takerAsset to sell in orders.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    ///         NOTE: makerAssetFilledAmount and takerAssetFilledAmount may include amounts filled of different assets.
+    function batchFillOrders(
+        LibOrder.Order[] memory orders,
+        uint256[] memory takerAssetFillAmounts,
+        bytes[] memory signatures
+    )
+        public
+        returns (FillResults memory totalFillResults)
+    {
+        for (uint256 i = 0; i < orders.length; i++) {
+            FillResults memory singleFillResults = fillOrder(
+                orders[i],
+                takerAssetFillAmounts[i],
+                signatures[i]
+            );
+            addFillResults(totalFillResults, singleFillResults);
+        }
+        return totalFillResults;
+    }
+
+    /// @dev Synchronously executes multiple calls of fillOrKill.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmounts Array of desired amounts of takerAsset to sell in orders.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    ///         NOTE: makerAssetFilledAmount and takerAssetFilledAmount may include amounts filled of different assets.
+    function batchFillOrKillOrders(
+        LibOrder.Order[] memory orders,
+        uint256[] memory takerAssetFillAmounts,
+        bytes[] memory signatures
+    )
+        public
+        returns (FillResults memory totalFillResults)
+    {
+        for (uint256 i = 0; i < orders.length; i++) {
+            FillResults memory singleFillResults = fillOrKillOrder(
+                orders[i],
+                takerAssetFillAmounts[i],
+                signatures[i]
+            );
+            addFillResults(totalFillResults, singleFillResults);
+        }
+        return totalFillResults;
+    }
+
+    /// @dev Fills an order with specified parameters and ECDSA signature.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmounts Array of desired amounts of takerAsset to sell in orders.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    ///         NOTE: makerAssetFilledAmount and takerAssetFilledAmount may include amounts filled of different assets.
+    function batchFillOrdersNoThrow(
+        LibOrder.Order[] memory orders,
+        uint256[] memory takerAssetFillAmounts,
+        bytes[] memory signatures
+    )
+        public
+        returns (FillResults memory totalFillResults)
+    {
+        for (uint256 i = 0; i < orders.length; i++) {
+            FillResults memory singleFillResults = fillOrderNoThrow(
+                orders[i],
+                takerAssetFillAmounts[i],
+                signatures[i]
+            );
+            addFillResults(totalFillResults, singleFillResults);
+        }
+        return totalFillResults;
+    }
+
+    /// @dev Synchronously executes multiple calls of fillOrder until total amount of takerAsset is sold by taker.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketSellOrders(
+        LibOrder.Order[] memory orders,
+        uint256 takerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        public
+        returns (FillResults memory totalFillResults)
+    {
+        bytes memory takerAssetData = orders[0].takerAssetData;
+    
+        for (uint256 i = 0; i < orders.length; i++) {
+
+            // We assume that asset being sold by taker is the same for each order.
+            // Rather than passing this in as calldata, we use the takerAssetData from the first order in all later orders.
+            orders[i].takerAssetData = takerAssetData;
+
+            // Calculate the remaining amount of takerAsset to sell
+            uint256 remainingTakerAssetFillAmount = safeSub(takerAssetFillAmount, totalFillResults.takerAssetFilledAmount);
+
+            // Attempt to sell the remaining amount of takerAsset
+            FillResults memory singleFillResults = fillOrder(
+                orders[i],
+                remainingTakerAssetFillAmount,
+                signatures[i]
+            );
+
+            // Update amounts filled and fees paid by maker and taker
+            addFillResults(totalFillResults, singleFillResults);
+
+            // Stop execution if the entire amount of takerAsset has been sold
+            if (totalFillResults.takerAssetFilledAmount == takerAssetFillAmount) {
+                break;
+            }
+        }
+        return totalFillResults;
+    }
+
+    /// @dev Synchronously executes multiple calls of fillOrder until total amount of takerAsset is sold by taker.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signatures Proofs that orders have been signed by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketSellOrdersNoThrow(
+        LibOrder.Order[] memory orders,
+        uint256 takerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        public
+        returns (FillResults memory totalFillResults)
+    {
+        bytes memory takerAssetData = orders[0].takerAssetData;
+
+        for (uint256 i = 0; i < orders.length; i++) {
+
+            // We assume that asset being sold by taker is the same for each order.
+            // Rather than passing this in as calldata, we use the takerAssetData from the first order in all later orders.
+            orders[i].takerAssetData = takerAssetData;
+
+            // Calculate the remaining amount of takerAsset to sell
+            uint256 remainingTakerAssetFillAmount = safeSub(takerAssetFillAmount, totalFillResults.takerAssetFilledAmount);
+
+            // Attempt to sell the remaining amount of takerAsset
+            FillResults memory singleFillResults = fillOrderNoThrow(
+                orders[i],
+                remainingTakerAssetFillAmount,
+                signatures[i]
+            );
+
+            // Update amounts filled and fees paid by maker and taker
+            addFillResults(totalFillResults, singleFillResults);
+
+            // Stop execution if the entire amount of takerAsset has been sold
+            if (totalFillResults.takerAssetFilledAmount == takerAssetFillAmount) {
+                break;
+            }
+        }
+        return totalFillResults;
+    }
+
+    /// @dev Synchronously executes multiple calls of fillOrder until total amount of makerAsset is bought by taker.
+    /// @param orders Array of order specifications.
+    /// @param makerAssetFillAmount Desired amount of makerAsset to buy.
+    /// @param signatures Proofs that orders have been signed by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketBuyOrders(
+        LibOrder.Order[] memory orders,
+        uint256 makerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        public
+        returns (FillResults memory totalFillResults)
+    {
+        bytes memory makerAssetData = orders[0].makerAssetData;
+
+        for (uint256 i = 0; i < orders.length; i++) {
+
+            // We assume that asset being bought by taker is the same for each order.
+            // Rather than passing this in as calldata, we copy the makerAssetData from the first order onto all later orders.
+            orders[i].makerAssetData = makerAssetData;
+
+            // Calculate the remaining amount of makerAsset to buy
+            uint256 remainingMakerAssetFillAmount = safeSub(makerAssetFillAmount, totalFillResults.makerAssetFilledAmount);
+
+            // Convert the remaining amount of makerAsset to buy into remaining amount
+            // of takerAsset to sell, assuming entire amount can be sold in the current order
+            uint256 remainingTakerAssetFillAmount = getPartialAmount(
+                orders[i].takerAssetAmount,
+                orders[i].makerAssetAmount,
+                remainingMakerAssetFillAmount
+            );
+
+            // Attempt to sell the remaining amount of takerAsset
+            FillResults memory singleFillResults = fillOrder(
+                orders[i],
+                remainingTakerAssetFillAmount,
+                signatures[i]
+            );
+
+            // Update amounts filled and fees paid by maker and taker
+            addFillResults(totalFillResults, singleFillResults);
+
+            // Stop execution if the entire amount of makerAsset has been bought
+            if (totalFillResults.makerAssetFilledAmount == makerAssetFillAmount) {
+                break;
+            }
+        }
+        return totalFillResults;
+    }
+
+    /// @dev Synchronously executes multiple fill orders in a single transaction until total amount is bought by taker.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param orders Array of order specifications.
+    /// @param makerAssetFillAmount Desired amount of makerAsset to buy.
+    /// @param signatures Proofs that orders have been signed by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketBuyOrdersNoThrow(
+        LibOrder.Order[] memory orders,
+        uint256 makerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        public
+        returns (FillResults memory totalFillResults)
+    {
+        bytes memory makerAssetData = orders[0].makerAssetData;
+
+        for (uint256 i = 0; i < orders.length; i++) {
+
+            // We assume that asset being bought by taker is the same for each order.
+            // Rather than passing this in as calldata, we copy the makerAssetData from the first order onto all later orders.
+            orders[i].makerAssetData = makerAssetData;
+
+            // Calculate the remaining amount of makerAsset to buy
+            uint256 remainingMakerAssetFillAmount = safeSub(makerAssetFillAmount, totalFillResults.makerAssetFilledAmount);
+
+            // Convert the remaining amount of makerAsset to buy into remaining amount
+            // of takerAsset to sell, assuming entire amount can be sold in the current order
+            uint256 remainingTakerAssetFillAmount = getPartialAmount(
+                orders[i].takerAssetAmount,
+                orders[i].makerAssetAmount,
+                remainingMakerAssetFillAmount
+            );
+
+            // Attempt to sell the remaining amount of takerAsset
+            FillResults memory singleFillResults = fillOrderNoThrow(
+                orders[i],
+                remainingTakerAssetFillAmount,
+                signatures[i]
+            );
+
+            // Update amounts filled and fees paid by maker and taker
+            addFillResults(totalFillResults, singleFillResults);
+
+            // Stop execution if the entire amount of makerAsset has been bought
+            if (totalFillResults.makerAssetFilledAmount == makerAssetFillAmount) {
+                break;
+            }
+        }
+        return totalFillResults;
+    }
+
+    /// @dev Synchronously cancels multiple orders in a single transaction.
+    /// @param orders Array of order specifications.
+    function batchCancelOrders(LibOrder.Order[] memory orders)
+        public
+    {
+        for (uint256 i = 0; i < orders.length; i++) {
+            cancelOrder(orders[i]);
+        }
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol
new file mode 100644
index 000000000..66f3b5796
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol
@@ -0,0 +1,36 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+contract IAssetProxyDispatcher {
+
+    /// @dev Registers an asset proxy to its asset proxy id.
+    ///      Once an asset proxy is registered, it cannot be unregistered.
+    /// @param assetProxy Address of new asset proxy to register.
+    function registerAssetProxy(address assetProxy)
+        external;
+
+    /// @dev Gets an asset proxy.
+    /// @param assetProxyId Id of the asset proxy.
+    /// @return The asset proxy registered to assetProxyId. Returns 0x0 if no proxy is registered.
+    function getAssetProxy(bytes4 assetProxyId)
+        external
+        view
+        returns (address);
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IExchange.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IExchange.sol
new file mode 100644
index 000000000..9f21c18d7
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IExchange.sol
@@ -0,0 +1,36 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./IExchangeCore.sol";
+import "./IMatchOrders.sol";
+import "./ISignatureValidator.sol";
+import "./ITransactions.sol";
+import "./IAssetProxyDispatcher.sol";
+import "./IWrapperFunctions.sol";
+
+contract IExchange is
+    IExchangeCore,
+    IMatchOrders,
+    ISignatureValidator,
+    ITransactions,
+    IAssetProxyDispatcher,
+    IWrapperFunctions
+{}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IExchangeCore.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IExchangeCore.sol
new file mode 100644
index 000000000..98222f33f
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IExchangeCore.sol
@@ -0,0 +1,59 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../libs/LibOrder.sol";
+import "../libs/LibFillResults.sol";
+
+contract IExchangeCore {
+
+    /// @dev Cancels all orders created by makerAddress with a salt less than or equal to the targetOrderEpoch
+    ///      and senderAddress equal to msg.sender (or null address if msg.sender == makerAddress).
+    /// @param targetOrderEpoch Orders created with a salt less or equal to this value will be cancelled.
+    function cancelOrdersUpTo(uint256 targetOrderEpoch)
+        external;
+
+    /// @dev Fills the input order.
+    /// @param order Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signature Proof that order has been created by maker.
+    /// @return Amounts filled and fees paid by maker and taker.
+    function fillOrder(
+        LibOrder.Order memory order,
+        uint256 takerAssetFillAmount,
+        bytes memory signature
+    )
+        public
+        returns (LibFillResults.FillResults memory fillResults);
+
+    /// @dev After calling, the order can not be filled anymore.
+    /// @param order Order struct containing order specifications.
+    function cancelOrder(LibOrder.Order memory order)
+        public;
+
+    /// @dev Gets information about an order: status, hash, and amount filled.
+    /// @param order Order to gather information on.
+    /// @return OrderInfo Information about the order and its state.
+    ///                   See LibOrder.OrderInfo for a complete description.
+    function getOrderInfo(LibOrder.Order memory order)
+        public
+        view
+        returns (LibOrder.OrderInfo memory orderInfo);
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IMatchOrders.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IMatchOrders.sol
new file mode 100644
index 000000000..df009d063
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IMatchOrders.sol
@@ -0,0 +1,44 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../libs/LibOrder.sol";
+import "../libs/LibFillResults.sol";
+
+contract IMatchOrders {
+
+    /// @dev Match two complementary orders that have a profitable spread.
+    ///      Each order is filled at their respective price point. However, the calculations are
+    ///      carried out as though the orders are both being filled at the right order's price point.
+    ///      The profit made by the left order goes to the taker (who matched the two orders).
+    /// @param leftOrder First order to match.
+    /// @param rightOrder Second order to match.
+    /// @param leftSignature Proof that order was created by the left maker.
+    /// @param rightSignature Proof that order was created by the right maker.
+    /// @return matchedFillResults Amounts filled and fees paid by maker and taker of matched orders.
+    /// TODO: Make this function external once supported by Solidity (See Solidity Issues #3199, #1603)
+    function matchOrders(
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder,
+        bytes memory leftSignature,
+        bytes memory rightSignature
+    )
+        public
+        returns (LibFillResults.MatchedFillResults memory matchedFillResults);
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/ISignatureValidator.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/ISignatureValidator.sol
new file mode 100644
index 000000000..511463309
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/ISignatureValidator.sol
@@ -0,0 +1,56 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+contract ISignatureValidator {
+
+    /// @dev Approves a hash on-chain using any valid signature type.
+    ///      After presigning a hash, the preSign signature type will become valid for that hash and signer.
+    /// @param signerAddress Address that should have signed the given hash.
+    /// @param signature Proof that the hash has been signed by signer.
+    function preSign(
+        bytes32 hash,
+        address signerAddress,
+        bytes signature
+    )
+        external;
+    
+    /// @dev Approves/unnapproves a Validator contract to verify signatures on signer's behalf.
+    /// @param validatorAddress Address of Validator contract.
+    /// @param approval Approval or disapproval of  Validator contract.
+    function setSignatureValidatorApproval(
+        address validatorAddress,
+        bool approval
+    )
+        external;
+
+    /// @dev Verifies that a signature is valid.
+    /// @param hash Message hash that is signed.
+    /// @param signerAddress Address of signer.
+    /// @param signature Proof of signing.
+    /// @return Validity of order signature.
+    function isValidSignature(
+        bytes32 hash,
+        address signerAddress,
+        bytes memory signature
+    )
+        public
+        view
+        returns (bool isValid);
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/ITransactions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/ITransactions.sol
new file mode 100644
index 000000000..a7cab8f55
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/ITransactions.sol
@@ -0,0 +1,34 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+pragma solidity ^0.4.24;
+
+contract ITransactions {
+
+    /// @dev Executes an exchange method call in the context of signer.
+    /// @param salt Arbitrary number to ensure uniqueness of transaction hash.
+    /// @param signerAddress Address of transaction signer.
+    /// @param data AbiV2 encoded calldata.
+    /// @param signature Proof of signer transaction by signer.
+    function executeTransaction(
+        uint256 salt,
+        address signerAddress,
+        bytes data,
+        bytes signature
+    )
+        external;
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IValidator.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IValidator.sol
new file mode 100644
index 000000000..0b1796a66
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IValidator.sol
@@ -0,0 +1,36 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.23;
+
+contract IValidator {
+
+    /// @dev Verifies that a signature is valid.
+    /// @param hash Message hash that is signed.
+    /// @param signerAddress Address that should have signed the given hash.
+    /// @param signature Proof of signing.
+    /// @return Validity of order signature.
+    function isValidSignature(
+        bytes32 hash,
+        address signerAddress,
+        bytes signature
+    )
+        external
+        view
+        returns (bool isValid);
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IWallet.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IWallet.sol
new file mode 100644
index 000000000..c86a2c057
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IWallet.sol
@@ -0,0 +1,34 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+contract IWallet {
+
+    /// @dev Verifies that a signature is valid.
+    /// @param hash Message hash that is signed.
+    /// @param signature Proof of signing.
+    /// @return Validity of order signature.
+    function isValidSignature(
+        bytes32 hash,
+        bytes signature
+    )
+        external
+        view
+        returns (bool isValid);
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IWrapperFunctions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IWrapperFunctions.sol
new file mode 100644
index 000000000..84bb683bc
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IWrapperFunctions.sol
@@ -0,0 +1,150 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../libs/LibOrder.sol";
+import "../libs/LibFillResults.sol";
+
+contract IWrapperFunctions {
+    /// @dev Fills the input order. Reverts if exact takerAssetFillAmount not filled.
+    /// @param order LibOrder.Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signature Proof that order has been created by maker.
+    function fillOrKillOrder(
+        LibOrder.Order memory order,
+        uint256 takerAssetFillAmount,
+        bytes memory signature
+    )
+        public
+        returns (LibFillResults.FillResults memory fillResults);
+
+    /// @dev Fills an order with specified parameters and ECDSA signature.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param order LibOrder.Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signature Proof that order has been created by maker.
+    /// @return Amounts filled and fees paid by maker and taker.
+    function fillOrderNoThrow(
+        LibOrder.Order memory order,
+        uint256 takerAssetFillAmount,
+        bytes memory signature
+    )
+        public
+        returns (LibFillResults.FillResults memory fillResults);
+
+    /// @dev Synchronously executes multiple calls of fillOrder.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmounts Array of desired amounts of takerAsset to sell in orders.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function batchFillOrders(
+        LibOrder.Order[] memory orders,
+        uint256[] memory takerAssetFillAmounts,
+        bytes[] memory signatures
+    )
+        public
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Synchronously executes multiple calls of fillOrKill.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmounts Array of desired amounts of takerAsset to sell in orders.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function batchFillOrKillOrders(
+        LibOrder.Order[] memory orders,
+        uint256[] memory takerAssetFillAmounts,
+        bytes[] memory signatures
+    )
+        public
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Fills an order with specified parameters and ECDSA signature.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmounts Array of desired amounts of takerAsset to sell in orders.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function batchFillOrdersNoThrow(
+        LibOrder.Order[] memory orders,
+        uint256[] memory takerAssetFillAmounts,
+        bytes[] memory signatures
+    )
+        public
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Synchronously executes multiple calls of fillOrder until total amount of takerAsset is sold by taker.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketSellOrders(
+        LibOrder.Order[] memory orders,
+        uint256 takerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        public
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Synchronously executes multiple calls of fillOrder until total amount of takerAsset is sold by taker.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signatures Proofs that orders have been signed by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketSellOrdersNoThrow(
+        LibOrder.Order[] memory orders,
+        uint256 takerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        public
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Synchronously executes multiple calls of fillOrder until total amount of makerAsset is bought by taker.
+    /// @param orders Array of order specifications.
+    /// @param makerAssetFillAmount Desired amount of makerAsset to buy.
+    /// @param signatures Proofs that orders have been signed by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketBuyOrders(
+        LibOrder.Order[] memory orders,
+        uint256 makerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        public
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Synchronously executes multiple fill orders in a single transaction until total amount is bought by taker.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param orders Array of order specifications.
+    /// @param makerAssetFillAmount Desired amount of makerAsset to buy.
+    /// @param signatures Proofs that orders have been signed by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketBuyOrdersNoThrow(
+        LibOrder.Order[] memory orders,
+        uint256 makerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        public
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Synchronously cancels multiple orders in a single transaction.
+    /// @param orders Array of order specifications.
+    function batchCancelOrders(LibOrder.Order[] memory orders)
+        public;
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibConstants.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibConstants.sol
new file mode 100644
index 000000000..488ca956c
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibConstants.sol
@@ -0,0 +1,34 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+contract LibConstants {
+   
+    // Asset data for ZRX token. Used for fee transfers.
+    // @TODO: Hardcode constant when we deploy. Currently 
+    //        not constant to make testing easier.
+    bytes public ZRX_ASSET_DATA;
+
+    // @TODO: Remove when we deploy.
+    constructor (bytes memory zrxAssetData)
+        public
+    {
+        ZRX_ASSET_DATA = zrxAssetData;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol
new file mode 100644
index 000000000..b983347a4
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol
@@ -0,0 +1,64 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+contract LibEIP712 {
+    // EIP191 header for EIP712 prefix
+    string constant EIP191_HEADER = "\x19\x01";
+
+    // EIP712 Domain Name value
+    string constant EIP712_DOMAIN_NAME = "0x Protocol";
+
+    // EIP712 Domain Version value
+    string constant EIP712_DOMAIN_VERSION = "2";
+
+    // Hash of the EIP712 Domain Separator Schema
+    bytes32 public constant EIP712_DOMAIN_SEPARATOR_SCHEMA_HASH = keccak256(abi.encodePacked(
+        "EIP712Domain(",
+        "string name,",
+        "string version,",
+        "address verifyingContract",
+        ")"
+    ));
+
+    // Hash of the EIP712 Domain Separator data
+    bytes32 public EIP712_DOMAIN_HASH;
+
+    constructor ()
+        public
+    {
+        EIP712_DOMAIN_HASH = keccak256(abi.encode(
+            EIP712_DOMAIN_SEPARATOR_SCHEMA_HASH,
+            keccak256(bytes(EIP712_DOMAIN_NAME)),
+            keccak256(bytes(EIP712_DOMAIN_VERSION)),
+            address(this)
+        ));
+    }
+
+    /// @dev Calculates EIP712 encoding for a hash struct in this EIP712 Domain.
+    /// @param hashStruct The EIP712 hash struct.
+    /// @return EIP712 hash applied to this EIP712 Domain.
+    function hashEIP712Message(bytes32 hashStruct)
+        internal
+        view
+        returns (bytes32)
+    {
+        return keccak256(abi.encodePacked(EIP191_HEADER, EIP712_DOMAIN_HASH, hashStruct));
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibExchangeErrors.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibExchangeErrors.sol
new file mode 100644
index 000000000..01aa78a1d
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibExchangeErrors.sol
@@ -0,0 +1,68 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+/// @dev This contract documents the revert reasons used in the Exchange contract.
+/// This contract is intended to serve as a reference, but is not actually used for efficiency reasons.
+contract LibExchangeErrors {
+
+    /// Order validation errors ///
+    string constant ORDER_UNFILLABLE = "ORDER_UNFILLABLE";                              // Order cannot be filled.
+    string constant INVALID_MAKER = "INVALID_MAKER";                                    // Invalid makerAddress.
+    string constant INVALID_TAKER = "INVALID_TAKER";                                    // Invalid takerAddress.
+    string constant INVALID_SENDER = "INVALID_SENDER";                                  // Invalid `msg.sender`.
+    string constant INVALID_ORDER_SIGNATURE = "INVALID_ORDER_SIGNATURE";                // Signature validation failed. 
+    
+    /// fillOrder validation errors ///
+    string constant INVALID_TAKER_AMOUNT = "INVALID_TAKER_AMOUNT";                      // takerAssetFillAmount cannot equal 0.
+    string constant ROUNDING_ERROR = "ROUNDING_ERROR";                                  // Rounding error greater than 0.1% of takerAssetFillAmount. 
+    
+    /// Signature validation errors ///
+    string constant INVALID_SIGNATURE = "INVALID_SIGNATURE";                            // Signature validation failed. 
+    string constant SIGNATURE_ILLEGAL = "SIGNATURE_ILLEGAL";                            // Signature type is illegal.
+    string constant SIGNATURE_UNSUPPORTED = "SIGNATURE_UNSUPPORTED";                    // Signature type unsupported.
+    
+    /// cancelOrdersUptTo errors ///
+    string constant INVALID_NEW_ORDER_EPOCH = "INVALID_NEW_ORDER_EPOCH";                // Specified salt must be greater than or equal to existing orderEpoch.
+
+    /// fillOrKillOrder errors ///
+    string constant COMPLETE_FILL_FAILED = "COMPLETE_FILL_FAILED";                      // Desired takerAssetFillAmount could not be completely filled. 
+
+    /// matchOrders errors ///
+    string constant NEGATIVE_SPREAD_REQUIRED = "NEGATIVE_SPREAD_REQUIRED";              // Matched orders must have a negative spread.
+
+    /// Transaction errors ///
+    string constant REENTRANCY_ILLEGAL = "REENTRANCY_ILLEGAL";                          // Recursive reentrancy is not allowed. 
+    string constant INVALID_TX_HASH = "INVALID_TX_HASH";                                // Transaction has already been executed. 
+    string constant INVALID_TX_SIGNATURE = "INVALID_TX_SIGNATURE";                      // Signature validation failed. 
+    string constant FAILED_EXECUTION = "FAILED_EXECUTION";                              // Transaction execution failed. 
+    
+    /// registerAssetProxy errors ///
+    string constant ASSET_PROXY_ALREADY_EXISTS = "ASSET_PROXY_ALREADY_EXISTS";          // AssetProxy with same id already exists.
+
+    /// dispatchTransferFrom errors ///
+    string constant ASSET_PROXY_DOES_NOT_EXIST = "ASSET_PROXY_DOES_NOT_EXIST";          // No assetProxy registered at given id.
+    string constant TRANSFER_FAILED = "TRANSFER_FAILED";                                // Asset transfer unsuccesful.
+
+    /// Length validation errors ///
+    string constant LENGTH_GREATER_THAN_0_REQUIRED = "LENGTH_GREATER_THAN_0_REQUIRED";  // Byte array must have a length greater than 0.
+    string constant LENGTH_GREATER_THAN_3_REQUIRED = "LENGTH_GREATER_THAN_3_REQUIRED";  // Byte array must have a length greater than 3.
+    string constant LENGTH_0_REQUIRED = "LENGTH_0_REQUIRED";                            // Byte array must have a length of 0.
+    string constant LENGTH_65_REQUIRED = "LENGTH_65_REQUIRED";                          // Byte array must have a length of 65.
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibFillResults.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibFillResults.sol
new file mode 100644
index 000000000..63f1b8c87
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibFillResults.sol
@@ -0,0 +1,53 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+import "../../../utils/SafeMath/SafeMath.sol";
+
+contract LibFillResults is
+    SafeMath
+{
+
+    struct FillResults {
+        uint256 makerAssetFilledAmount;  // Total amount of makerAsset(s) filled.
+        uint256 takerAssetFilledAmount;  // Total amount of takerAsset(s) filled.
+        uint256 makerFeePaid;            // Total amount of ZRX paid by maker(s) to feeRecipient(s).
+        uint256 takerFeePaid;            // Total amount of ZRX paid by taker to feeRecipients(s).
+    }
+
+    struct MatchedFillResults {
+        FillResults left;                    // Amounts filled and fees paid of left order.
+        FillResults right;                   // Amounts filled and fees paid of right order.
+        uint256 leftMakerAssetSpreadAmount;  // Spread between price of left and right order, denominated in the left order's makerAsset, paid to taker.
+    }
+
+    /// @dev Adds properties of both FillResults instances.
+    ///      Modifies the first FillResults instance specified.
+    /// @param totalFillResults Fill results instance that will be added onto.
+    /// @param singleFillResults Fill results instance that will be added to totalFillResults.
+    function addFillResults(FillResults memory totalFillResults, FillResults memory singleFillResults)
+        internal
+        pure
+    {
+        totalFillResults.makerAssetFilledAmount = safeAdd(totalFillResults.makerAssetFilledAmount, singleFillResults.makerAssetFilledAmount);
+        totalFillResults.takerAssetFilledAmount = safeAdd(totalFillResults.takerAssetFilledAmount, singleFillResults.takerAssetFilledAmount);
+        totalFillResults.makerFeePaid = safeAdd(totalFillResults.makerFeePaid, singleFillResults.makerFeePaid);
+        totalFillResults.takerFeePaid = safeAdd(totalFillResults.takerFeePaid, singleFillResults.takerFeePaid);
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibMath.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibMath.sol
new file mode 100644
index 000000000..bfe2fd33f
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibMath.sol
@@ -0,0 +1,72 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+import "../../../utils/SafeMath/SafeMath.sol";
+
+contract LibMath is
+    SafeMath
+{
+
+    /// @dev Calculates partial value given a numerator and denominator.
+    /// @param numerator Numerator.
+    /// @param denominator Denominator.
+    /// @param target Value to calculate partial of.
+    /// @return Partial value of target.
+    function getPartialAmount(
+        uint256 numerator,
+        uint256 denominator,
+        uint256 target)
+        internal
+        pure
+        returns (uint256 partialAmount)
+    {
+        partialAmount = safeDiv(
+            safeMul(numerator, target),
+            denominator
+        );
+        return partialAmount;
+    }
+
+    /// @dev Checks if rounding error > 0.1%.
+    /// @param numerator Numerator.
+    /// @param denominator Denominator.
+    /// @param target Value to multiply with numerator/denominator.
+    /// @return Rounding error is present.
+    function isRoundingError(
+        uint256 numerator,
+        uint256 denominator,
+        uint256 target)
+        internal
+        pure
+        returns (bool isError)
+    {
+        uint256 remainder = mulmod(target, numerator, denominator);
+        if (remainder == 0) {
+            return false; // No rounding error.
+        }
+
+        uint256 errPercentageTimes1000000 = safeDiv(
+            safeMul(remainder, 1000000),
+            safeMul(numerator, target)
+        );
+        isError = errPercentageTimes1000000 > 1000;
+        return isError;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol
new file mode 100644
index 000000000..954f94f76
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol
@@ -0,0 +1,135 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+import "./LibEIP712.sol";
+
+contract LibOrder is
+    LibEIP712
+{
+
+    // Hash for the EIP712 Order Schema
+    bytes32 constant EIP712_ORDER_SCHEMA_HASH = keccak256(abi.encodePacked(
+        "Order(",
+        "address makerAddress,",
+        "address takerAddress,",
+        "address feeRecipientAddress,",
+        "address senderAddress,",
+        "uint256 makerAssetAmount,",
+        "uint256 takerAssetAmount,",
+        "uint256 makerFee,",
+        "uint256 takerFee,",
+        "uint256 expirationTimeSeconds,",
+        "uint256 salt,",
+        "bytes makerAssetData,",
+        "bytes takerAssetData",
+        ")"
+    ));
+
+    // A valid order remains fillable until it is expired, fully filled, or cancelled.
+    // An order's state is unaffected by external factors, like account balances.
+    enum OrderStatus {
+        INVALID,                     // Default value
+        INVALID_MAKER_ASSET_AMOUNT,  // Order does not have a valid maker asset amount
+        INVALID_TAKER_ASSET_AMOUNT,  // Order does not have a valid taker asset amount
+        FILLABLE,                    // Order is fillable
+        EXPIRED,                     // Order has already expired
+        FULLY_FILLED,                // Order is fully filled
+        CANCELLED                    // Order has been cancelled
+    }
+
+    struct Order {
+        address makerAddress;           // Address that created the order.      
+        address takerAddress;           // Address that is allowed to fill the order. If set to 0, any address is allowed to fill the order.          
+        address feeRecipientAddress;    // Address that will recieve fees when order is filled.      
+        address senderAddress;          // Address that is allowed to call Exchange contract methods that affect this order. If set to 0, any address is allowed to call these methods.
+        uint256 makerAssetAmount;       // Amount of makerAsset being offered by maker. Must be greater than 0.        
+        uint256 takerAssetAmount;       // Amount of takerAsset being bid on by maker. Must be greater than 0.        
+        uint256 makerFee;               // Amount of ZRX paid to feeRecipient by maker when order is filled. If set to 0, no transfer of ZRX from maker to feeRecipient will be attempted.
+        uint256 takerFee;               // Amount of ZRX paid to feeRecipient by taker when order is filled. If set to 0, no transfer of ZRX from taker to feeRecipient will be attempted.
+        uint256 expirationTimeSeconds;  // Timestamp in seconds at which order expires.          
+        uint256 salt;                   // Arbitrary number to facilitate uniqueness of the order's hash.     
+        bytes makerAssetData;           // Encoded data that can be decoded by a specified proxy contract when transferring makerAsset. The last byte references the id of this proxy.
+        bytes takerAssetData;           // Encoded data that can be decoded by a specified proxy contract when transferring takerAsset. The last byte references the id of this proxy.
+    }
+
+    struct OrderInfo {
+        uint8 orderStatus;                    // Status that describes order's validity and fillability.
+        bytes32 orderHash;                    // EIP712 hash of the order (see LibOrder.getOrderHash).
+        uint256 orderTakerAssetFilledAmount;  // Amount of order that has already been filled.
+    }
+
+    /// @dev Calculates Keccak-256 hash of the order.
+    /// @param order The order structure.
+    /// @return Keccak-256 EIP712 hash of the order.
+    function getOrderHash(Order memory order)
+        internal
+        view
+        returns (bytes32 orderHash)
+    {
+        orderHash = hashEIP712Message(hashOrder(order));
+        return orderHash;
+    }
+
+    /// @dev Calculates EIP712 hash of the order.
+    /// @param order The order structure.
+    /// @return EIP712 hash of the order.
+    function hashOrder(Order memory order)
+        internal
+        pure
+        returns (bytes32 result)
+    {
+        bytes32 schemaHash = EIP712_ORDER_SCHEMA_HASH;
+        bytes32 makerAssetDataHash = keccak256(order.makerAssetData);
+        bytes32 takerAssetDataHash = keccak256(order.takerAssetData);
+        // Assembly for more efficiently computing:
+        //   keccak256(abi.encode(
+        //       order.makerAddress,
+        //       order.takerAddress,
+        //       order.feeRecipientAddress,
+        //       order.senderAddress,
+        //       order.makerAssetAmount,
+        //       order.takerAssetAmount,
+        //       order.makerFee,
+        //       order.takerFee,
+        //       order.expirationTimeSeconds,
+        //       order.salt,
+        //       keccak256(order.makerAssetData),
+        //       keccak256(order.takerAssetData)
+        //   ));
+        assembly {
+            // Backup
+            let temp1 := mload(sub(order,  32))
+            let temp2 := mload(add(order, 320))
+            let temp3 := mload(add(order, 352))
+            
+            // Hash in place
+            mstore(sub(order,  32), schemaHash)
+            mstore(add(order, 320), makerAssetDataHash)
+            mstore(add(order, 352), takerAssetDataHash)
+            result := keccak256(sub(order, 32), 416)
+            
+            // Restore
+            mstore(sub(order,  32), temp1)
+            mstore(add(order, 320), temp2)
+            mstore(add(order, 352), temp3)
+        }
+        return result;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MAssetProxyDispatcher.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
new file mode 100644
index 000000000..5bf59c6ce
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
@@ -0,0 +1,46 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../interfaces/IAssetProxyDispatcher.sol";
+
+contract MAssetProxyDispatcher is
+    IAssetProxyDispatcher
+{
+
+    // Logs registration of new asset proxy
+    event AssetProxyRegistered(
+        bytes4 id,              // Id of new registered AssetProxy.
+        address assetProxy      // Address of new registered AssetProxy.
+    );
+
+    /// @dev Forwards arguments to assetProxy and calls `transferFrom`. Either succeeds or throws.
+    /// @param assetData Byte array encoded for the asset.
+    /// @param from Address to transfer token from.
+    /// @param to Address to transfer token to.
+    /// @param amount Amount of token to transfer.
+    function dispatchTransferFrom(
+        bytes memory assetData,
+        address from,
+        address to,
+        uint256 amount
+    )
+        internal;
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MExchangeCore.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MExchangeCore.sol
new file mode 100644
index 000000000..6e406e1c4
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MExchangeCore.sol
@@ -0,0 +1,127 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../libs/LibOrder.sol";
+import "../libs/LibFillResults.sol";
+import "../interfaces/IExchangeCore.sol";
+
+contract MExchangeCore is
+    IExchangeCore
+{
+    // Fill event is emitted whenever an order is filled.
+    event Fill(
+        address indexed makerAddress,         // Address that created the order.      
+        address indexed feeRecipientAddress,  // Address that received fees.
+        address takerAddress,                 // Address that filled the order.
+        address senderAddress,                // Address that called the Exchange contract (msg.sender).
+        uint256 makerAssetFilledAmount,       // Amount of makerAsset sold by maker and bought by taker. 
+        uint256 takerAssetFilledAmount,       // Amount of takerAsset sold by taker and bought by maker.
+        uint256 makerFeePaid,                 // Amount of ZRX paid to feeRecipient by maker.
+        uint256 takerFeePaid,                 // Amount of ZRX paid to feeRecipient by taker.
+        bytes32 indexed orderHash,            // EIP712 hash of order (see LibOrder.getOrderHash).
+        bytes makerAssetData,                 // Encoded data specific to makerAsset. 
+        bytes takerAssetData                  // Encoded data specific to takerAsset.
+    );
+
+    // Cancel event is emitted whenever an individual order is cancelled.
+    event Cancel(
+        address indexed makerAddress,         // Address that created the order.      
+        address indexed feeRecipientAddress,  // Address that would have recieved fees if order was filled.   
+        address senderAddress,                // Address that called the Exchange contract (msg.sender).
+        bytes32 indexed orderHash,            // EIP712 hash of order (see LibOrder.getOrderHash).
+        bytes makerAssetData,                 // Encoded data specific to makerAsset. 
+        bytes takerAssetData                  // Encoded data specific to takerAsset.
+    );
+
+    // CancelUpTo event is emitted whenever `cancelOrdersUpTo` is executed succesfully.
+    event CancelUpTo(
+        address indexed makerAddress,         // Orders cancelled must have been created by this address.
+        address indexed senderAddress,        // Orders cancelled must have a `senderAddress` equal to this address.
+        uint256 orderEpoch                    // Orders specified makerAddress and senderAddress with a salt <= this value are considered cancelled.
+    );
+
+    /// @dev Updates state with results of a fill order.
+    /// @param order that was filled.
+    /// @param takerAddress Address of taker who filled the order.
+    /// @param orderTakerAssetFilledAmount Amount of order already filled.
+    /// @return fillResults Amounts filled and fees paid by maker and taker.
+    function updateFilledState(
+        LibOrder.Order memory order,
+        address takerAddress,
+        bytes32 orderHash,
+        uint256 orderTakerAssetFilledAmount,
+        LibFillResults.FillResults memory fillResults
+    )
+        internal;
+
+    /// @dev Updates state with results of cancelling an order.
+    ///      State is only updated if the order is currently fillable.
+    ///      Otherwise, updating state would have no effect.
+    /// @param order that was cancelled.
+    /// @param orderHash Hash of order that was cancelled.
+    function updateCancelledState(
+        LibOrder.Order memory order,
+        bytes32 orderHash
+    )
+        internal;
+
+    /// @dev Validates context for fillOrder. Succeeds or throws.
+    /// @param order to be filled.
+    /// @param orderInfo Status, orderHash, and amount already filled of order.
+    /// @param takerAddress Address of order taker.
+    /// @param takerAssetFillAmount Desired amount of order to fill by taker.
+    /// @param takerAssetFilledAmount Amount of takerAsset that will be filled.
+    /// @param signature Proof that the orders was created by its maker.
+    function assertValidFill(
+        LibOrder.Order memory order,
+        LibOrder.OrderInfo memory orderInfo,
+        address takerAddress,
+        uint256 takerAssetFillAmount,
+        uint256 takerAssetFilledAmount,
+        bytes memory signature
+    )
+        internal
+        view;
+
+
+    /// @dev Validates context for cancelOrder. Succeeds or throws.
+    /// @param order to be cancelled.
+    /// @param orderInfo OrderStatus, orderHash, and amount already filled of order.
+    function assertValidCancel(
+        LibOrder.Order memory order,
+        LibOrder.OrderInfo memory orderInfo
+    )
+        internal
+        view;
+
+    /// @dev Calculates amounts filled and fees paid by maker and taker.
+    /// @param order to be filled.
+    /// @param takerAssetFilledAmount Amount of takerAsset that will be filled.
+    /// @return fillResults Amounts filled and fees paid by maker and taker.
+    function calculateFillResults(
+        LibOrder.Order memory order,
+        uint256 takerAssetFilledAmount
+    )
+        internal
+        pure
+        returns (LibFillResults.FillResults memory fillResults);
+
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MMatchOrders.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MMatchOrders.sol
new file mode 100644
index 000000000..abe7c3596
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MMatchOrders.sol
@@ -0,0 +1,58 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../libs/LibOrder.sol";
+import "../libs/LibFillResults.sol";
+import "../interfaces/IMatchOrders.sol";
+
+contract MMatchOrders is
+    IMatchOrders
+{
+
+    /// @dev Validates context for matchOrders. Succeeds or throws.
+    /// @param leftOrder First order to match.
+    /// @param rightOrder Second order to match.
+    function assertValidMatch(
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder
+    )
+        internal
+        pure;
+
+    /// @dev Calculates fill amounts for the matched orders.
+    ///      Each order is filled at their respective price point. However, the calculations are
+    ///      carried out as though the orders are both being filled at the right order's price point.
+    ///      The profit made by the leftOrder order goes to the taker (who matched the two orders).
+    /// @param leftOrder First order to match.
+    /// @param rightOrder Second order to match.
+    /// @param leftOrderTakerAssetFilledAmount Amount of left order already filled.
+    /// @param rightOrderTakerAssetFilledAmount Amount of right order already filled.
+    /// @param matchedFillResults Amounts to fill and fees to pay by maker and taker of matched orders.
+    function calculateMatchedFillResults(
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder,
+        uint256 leftOrderTakerAssetFilledAmount,
+        uint256 rightOrderTakerAssetFilledAmount
+    )
+        internal
+        pure
+        returns (LibFillResults.MatchedFillResults memory matchedFillResults);
+
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MSignatureValidator.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MSignatureValidator.sol
new file mode 100644
index 000000000..6cc1d7a10
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MSignatureValidator.sol
@@ -0,0 +1,45 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+import "../interfaces/ISignatureValidator.sol";
+
+contract MSignatureValidator is
+    ISignatureValidator
+{
+    event SignatureValidatorApproval(
+        address indexed signerAddress,     // Address that approves or disapproves a contract to verify signatures.
+        address indexed validatorAddress,  // Address of signature validator contract.
+        bool approved                      // Approval or disapproval of validator contract.
+    );
+
+    // Allowed signature types.
+    enum SignatureType {
+        Illegal,         // 0x00, default value
+        Invalid,         // 0x01
+        EIP712,          // 0x02
+        EthSign,         // 0x03
+        Caller,          // 0x04
+        Wallet,          // 0x05
+        Validator,       // 0x06
+        PreSigned,       // 0x07
+        Trezor,          // 0x08
+        NSignatureTypes  // 0x09, number of signature types. Always leave at end.
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MTransactions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MTransactions.sol
new file mode 100644
index 000000000..e2f89de01
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MTransactions.sol
@@ -0,0 +1,35 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+pragma solidity ^0.4.24;
+
+import "../interfaces/ITransactions.sol";
+
+contract MTransactions is
+    ITransactions
+{
+
+    /// @dev The current function will be called in the context of this address (either 0x transaction signer or `msg.sender`).
+    ///      If calling a fill function, this address will represent the taker.
+    ///      If calling a cancel function, this address will represent the maker.
+    /// @return Signer of 0x transaction if entry point is `executeTransaction`.
+    ///         `msg.sender` if entry point is any other function.
+    function getCurrentContextAddress()
+        internal
+        view
+        returns (address);
+}
diff --git a/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyERC20Token.sol b/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyERC20Token.sol
new file mode 100644
index 000000000..b2fe2df06
--- /dev/null
+++ b/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyERC20Token.sol
@@ -0,0 +1,57 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../Mintable/Mintable.sol";
+import "../../utils/Ownable/Ownable.sol";
+
+contract DummyERC20Token is Mintable, Ownable {
+    string public name;
+    string public symbol;
+    uint256 public decimals;
+
+    constructor (
+        string _name,
+        string _symbol,
+        uint256 _decimals,
+        uint256 _totalSupply
+    )
+        public
+    {
+        name = _name;
+        symbol = _symbol;
+        decimals = _decimals;
+        totalSupply = _totalSupply;
+        balances[msg.sender] = _totalSupply;
+    }
+
+    function setBalance(address _target, uint256 _value)
+        public
+        onlyOwner
+    {
+        uint256 currBalance = balanceOf(_target);
+        if (_value < currBalance) {
+            totalSupply = safeSub(totalSupply, safeSub(currBalance, _value));
+        } else {
+            totalSupply = safeAdd(totalSupply, safeSub(_value, currBalance));
+        }
+        balances[_target] = _value;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/test/DummyERC721Receiver/DummyERC721Receiver.sol b/packages/contracts/src/2.0.0/test/DummyERC721Receiver/DummyERC721Receiver.sol
new file mode 100644
index 000000000..c584d0b54
--- /dev/null
+++ b/packages/contracts/src/2.0.0/test/DummyERC721Receiver/DummyERC721Receiver.sol
@@ -0,0 +1,63 @@
+/*
+The MIT License (MIT)
+
+Copyright (c) 2016 Smart Contract Solutions, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+pragma solidity ^0.4.24;
+
+import "../../tokens/ERC721Token/IERC721Receiver.sol";
+
+contract DummyERC721Receiver is
+    IERC721Receiver
+{
+
+    event TokenReceived(
+        address from,
+        uint256 tokenId,
+        bytes data
+    );
+
+    /**
+    * @notice Handle the receipt of an NFT
+    * @dev The ERC721 smart contract calls this function on the recipient
+    *  after a `safetransfer`. This function MAY throw to revert and reject the
+    *  transfer. This function MUST use 50,000 gas or less. Return of other
+    *  than the magic value MUST result in the transaction being reverted.
+    *  Note: the contract address is always the message sender.
+    * @param _from The sending address
+    * @param _tokenId The NFT identifier which is being transfered
+    * @param _data Additional data with no specified format
+    * @return `bytes4(keccak256("onERC721Received(address,uint256,bytes)"))`
+    */
+    function onERC721Received(
+        address _from,
+        uint256 _tokenId,
+        bytes _data
+    )
+        public
+        returns (bytes4)
+    {
+        emit TokenReceived(_from, _tokenId, _data);
+        return ERC721_RECEIVED;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/test/DummyERC721Token/DummyERC721Token.sol b/packages/contracts/src/2.0.0/test/DummyERC721Token/DummyERC721Token.sol
new file mode 100644
index 000000000..78ea96447
--- /dev/null
+++ b/packages/contracts/src/2.0.0/test/DummyERC721Token/DummyERC721Token.sol
@@ -0,0 +1,75 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../tokens/ERC721Token/ERC721Token.sol";
+import "../../utils/Ownable/Ownable.sol";
+
+contract DummyERC721Token is
+    Ownable,
+    ERC721Token
+{
+
+    /**
+    * @dev Constructor passes its arguments to the base ERC721Token constructor
+    * @param name of token
+    * @param symbol of token
+    */
+    constructor (
+        string name,
+        string symbol
+    )
+        public
+        ERC721Token(name, symbol)
+    {}
+
+    /**
+    * @dev Function to mint a new token
+    * @dev Reverts if the given token ID already exists
+    * @param to address the beneficiary that will own the minted token
+    * @param tokenId uint256 ID of the token to be minted by the msg.sender
+    */
+    function mint(address to, uint256 tokenId)
+        public
+        onlyOwner
+    {
+        require(
+            !exists(tokenId),
+            "Token with tokenId already exists."
+        );
+        _mint(to, tokenId);
+    }
+
+    /**
+    * @dev Function to burn a token
+    * @dev Reverts if the given token ID doesn't exist
+    * @param tokenId uint256 ID of the token to be minted by the msg.sender
+    */
+    function burn(address owner, uint256 tokenId)
+        public
+        onlyOwner
+    {
+        require(
+            exists(tokenId),
+            "Token with tokenId does not exist."
+        );
+        _burn(owner, tokenId);
+    }
+}
diff --git a/packages/contracts/src/2.0.0/test/ExchangeWrapper/ExchangeWrapper.sol b/packages/contracts/src/2.0.0/test/ExchangeWrapper/ExchangeWrapper.sol
new file mode 100644
index 000000000..5baaf6e5a
--- /dev/null
+++ b/packages/contracts/src/2.0.0/test/ExchangeWrapper/ExchangeWrapper.sol
@@ -0,0 +1,98 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../protocol/Exchange/interfaces/IExchange.sol";
+import "../../protocol/Exchange/libs/LibOrder.sol";
+
+contract ExchangeWrapper {
+
+    // Exchange contract.
+    IExchange EXCHANGE;
+
+    constructor (address _exchange)
+        public
+    {
+        EXCHANGE = IExchange(_exchange);
+    }
+
+    /// @dev Fills an order using `msg.sender` as the taker.
+    /// @param order Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param salt Arbitrary value to gaurantee uniqueness of 0x transaction hash.
+    /// @param orderSignature Proof that order has been created by maker.
+    /// @param takerSignature Proof that taker wishes to call this function with given params.
+    function fillOrder(
+        LibOrder.Order memory order,
+        uint256 takerAssetFillAmount,
+        uint256 salt,
+        bytes memory orderSignature,
+        bytes memory takerSignature
+    )
+        public
+    {
+        address takerAddress = msg.sender;
+
+        // Encode arguments into byte array.
+        bytes memory data = abi.encodeWithSelector(
+            EXCHANGE.fillOrder.selector,
+            order,
+            takerAssetFillAmount,
+            orderSignature
+        );
+
+        // Call `fillOrder` via `executeTransaction`.
+        EXCHANGE.executeTransaction(
+            salt,
+            takerAddress,
+            data,
+            takerSignature
+        );
+    }
+
+    /// @dev Cancels all orders created by sender with a salt less than or equal to the targetOrderEpoch
+    ///      and senderAddress equal to this contract.
+    /// @param targetOrderEpoch Orders created with a salt less or equal to this value will be cancelled.
+    /// @param salt Arbitrary value to gaurantee uniqueness of 0x transaction hash.
+    /// @param makerSignature Proof that maker wishes to call this function with given params.
+    function cancelOrdersUpTo(
+        uint256 targetOrderEpoch,
+        uint256 salt,
+        bytes makerSignature
+    )
+        external
+    {
+        address makerAddress = msg.sender;
+
+        // Encode arguments into byte array.
+        bytes memory data = abi.encodeWithSelector(
+            EXCHANGE.cancelOrdersUpTo.selector,
+            targetOrderEpoch
+        );
+
+        // Call `cancelOrdersUpTo` via `executeTransaction`.
+        EXCHANGE.executeTransaction(
+            salt,
+            makerAddress,
+            data,
+            makerSignature
+        );
+    }
+}
diff --git a/packages/contracts/src/2.0.0/test/Mintable/Mintable.sol b/packages/contracts/src/2.0.0/test/Mintable/Mintable.sol
new file mode 100644
index 000000000..a91bfee9e
--- /dev/null
+++ b/packages/contracts/src/2.0.0/test/Mintable/Mintable.sol
@@ -0,0 +1,40 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../tokens/UnlimitedAllowanceToken/UnlimitedAllowanceToken.sol";
+import "../../utils/SafeMath/SafeMath.sol";
+
+/*
+ * Mintable
+ * Base contract that creates a mintable UnlimitedAllowanceToken
+ */
+contract Mintable is UnlimitedAllowanceToken, SafeMath {
+    function mint(uint256 _value)
+        public
+    {
+        require(
+            _value <= 100000000000000000000,
+            "Minting more than 100000000000000000000 is not allowed."
+        );
+        balances[msg.sender] = safeAdd(_value, balances[msg.sender]);
+        totalSupply = safeAdd(totalSupply, _value);
+    }
+}
diff --git a/packages/contracts/src/2.0.0/test/TestAssetProxyDispatcher/TestAssetProxyDispatcher.sol b/packages/contracts/src/2.0.0/test/TestAssetProxyDispatcher/TestAssetProxyDispatcher.sol
new file mode 100644
index 000000000..2ae69e0ef
--- /dev/null
+++ b/packages/contracts/src/2.0.0/test/TestAssetProxyDispatcher/TestAssetProxyDispatcher.sol
@@ -0,0 +1,34 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../protocol/Exchange/MixinAssetProxyDispatcher.sol";
+
+contract TestAssetProxyDispatcher is MixinAssetProxyDispatcher {
+    function publicDispatchTransferFrom(
+        bytes memory assetData,
+        address from,
+        address to,
+        uint256 amount)
+        public
+    {
+        dispatchTransferFrom(assetData, from, to, amount);
+    }
+}
diff --git a/packages/contracts/src/2.0.0/test/TestAssetProxyOwner/TestAssetProxyOwner.sol b/packages/contracts/src/2.0.0/test/TestAssetProxyOwner/TestAssetProxyOwner.sol
new file mode 100644
index 000000000..2abcd17a0
--- /dev/null
+++ b/packages/contracts/src/2.0.0/test/TestAssetProxyOwner/TestAssetProxyOwner.sol
@@ -0,0 +1,56 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+import "../../protocol/AssetProxyOwner/AssetProxyOwner.sol";
+
+contract TestAssetProxyOwner is
+    AssetProxyOwner
+{
+    constructor(
+        address[] memory _owners,
+        address[] memory _assetProxyContracts,
+        uint256 _required,
+        uint256 _secondsTimeLocked
+    )
+        public
+        AssetProxyOwner(_owners, _assetProxyContracts, _required, _secondsTimeLocked)
+    {
+    }
+    
+    function testValidRemoveAuthorizedAddressAtIndexTx(uint256 id)
+        public
+        validRemoveAuthorizedAddressAtIndexTx(id)
+        returns (bool)
+    {
+        // Do nothing. We expect reverts through the modifier
+        return true;
+    }
+    
+    /// @dev Compares first 4 bytes of byte array to `removeAuthorizedAddressAtIndex` function selector.
+    /// @param data Transaction data.
+    /// @return Successful if data is a call to `removeAuthorizedAddressAtIndex`.
+    function isFunctionRemoveAuthorizedAddressAtIndex(bytes memory data)
+        public
+        pure
+        returns (bool)
+    {
+        return data.readBytes4(0) == REMOVE_AUTHORIZED_ADDRESS_AT_INDEX_SELECTOR;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/test/TestLibBytes/TestLibBytes.sol b/packages/contracts/src/2.0.0/test/TestLibBytes/TestLibBytes.sol
new file mode 100644
index 000000000..f45faaf36
--- /dev/null
+++ b/packages/contracts/src/2.0.0/test/TestLibBytes/TestLibBytes.sol
@@ -0,0 +1,269 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../utils/LibBytes/LibBytes.sol";
+
+contract TestLibBytes {
+    
+    using LibBytes for bytes;
+
+    /// @dev Pops the last byte off of a byte array by modifying its length.
+    /// @param b Byte array that will be modified.
+    /// @return The byte that was popped off.
+    function publicPopLastByte(bytes memory b)
+        public
+        pure
+        returns (bytes memory, bytes1 result)
+    {
+        result = b.popLastByte();
+        return (b, result);
+    }
+
+    /// @dev Pops the last 20 bytes off of a byte array by modifying its length.
+    /// @param b Byte array that will be modified.
+    /// @return The 20 byte address that was popped off.
+    function publicPopLast20Bytes(bytes memory b)
+        public
+        pure
+        returns (bytes memory, address result)
+    {
+        result = b.popLast20Bytes();
+        return (b, result);
+    }
+
+    /// @dev Tests equality of two byte arrays.
+    /// @param lhs First byte array to compare.
+    /// @param rhs Second byte array to compare.
+    /// @return True if arrays are the same. False otherwise.
+    function publicEquals(bytes memory lhs, bytes memory rhs)
+        public
+        pure
+        returns (bool equal)
+    {
+        equal = lhs.equals(rhs);
+        return equal;
+    }
+    
+    function publicEqualsPop1(bytes memory lhs, bytes memory rhs)
+        public
+        pure
+        returns (bool equal)
+    {
+        lhs.popLastByte();
+        rhs.popLastByte();
+        equal = lhs.equals(rhs);
+        return equal;
+    }
+
+    /// @dev Performs a deep copy of a byte array onto another byte array of greater than or equal length.
+    /// @param dest Byte array that will be overwritten with source bytes.
+    /// @param source Byte array to copy onto dest bytes.
+    function publicDeepCopyBytes(
+        bytes memory dest,
+        bytes memory source
+    )
+        public
+        pure
+        returns (bytes memory)
+    {
+        LibBytes.deepCopyBytes(dest, source);
+        return dest;
+    }
+
+    /// @dev Reads an address from a position in a byte array.
+    /// @param b Byte array containing an address.
+    /// @param index Index in byte array of address.
+    /// @return address from byte array.
+    function publicReadAddress(
+        bytes memory b,
+        uint256 index
+    )
+        public
+        pure
+        returns (address result)
+    {
+        result = b.readAddress(index);
+        return result;
+    }
+
+    /// @dev Writes an address into a specific position in a byte array.
+    /// @param b Byte array to insert address into.
+    /// @param index Index in byte array of address.
+    /// @param input Address to put into byte array.
+    function publicWriteAddress(
+        bytes memory b,
+        uint256 index,
+        address input
+    )
+        public
+        pure
+        returns (bytes memory)
+    {
+        b.writeAddress(index, input);
+        return b;
+    }
+
+    /// @dev Reads a bytes32 value from a position in a byte array.
+    /// @param b Byte array containing a bytes32 value.
+    /// @param index Index in byte array of bytes32 value.
+    /// @return bytes32 value from byte array.
+    function publicReadBytes32(
+        bytes memory b,
+        uint256 index
+    )
+        public
+        pure
+        returns (bytes32 result)
+    {
+        result = b.readBytes32(index);
+        return result;
+    }
+
+    /// @dev Writes a bytes32 into a specific position in a byte array.
+    /// @param b Byte array to insert <input> into.
+    /// @param index Index in byte array of <input>.
+    /// @param input bytes32 to put into byte array.
+    function publicWriteBytes32(
+        bytes memory b,
+        uint256 index,
+        bytes32 input
+    )
+        public
+        pure
+        returns (bytes memory)
+    {
+        b.writeBytes32(index, input);
+        return b;
+    }
+
+    /// @dev Reads a uint256 value from a position in a byte array.
+    /// @param b Byte array containing a uint256 value.
+    /// @param index Index in byte array of uint256 value.
+    /// @return uint256 value from byte array.
+    function publicReadUint256(
+        bytes memory b,
+        uint256 index
+    )
+        public
+        pure
+        returns (uint256 result)
+    {
+        result = b.readUint256(index);
+        return result;
+    }
+
+    /// @dev Writes a uint256 into a specific position in a byte array.
+    /// @param b Byte array to insert <input> into.
+    /// @param index Index in byte array of <input>.
+    /// @param input uint256 to put into byte array.
+    function publicWriteUint256(
+        bytes memory b,
+        uint256 index,
+        uint256 input
+    )
+        public
+        pure
+        returns (bytes memory)
+    {
+        b.writeUint256(index, input);
+        return b;
+    }
+
+    /// @dev Reads an unpadded bytes4 value from a position in a byte array.
+    /// @param b Byte array containing a bytes4 value.
+    /// @param index Index in byte array of bytes4 value.
+    /// @return bytes4 value from byte array.
+    function publicReadBytes4(
+        bytes memory b,
+        uint256 index
+    )
+        public
+        pure
+        returns (bytes4 result)
+    {
+        result = b.readBytes4(index);
+        return result;
+    }
+
+    /// @dev Reads nested bytes from a specific position.
+    /// @param b Byte array containing nested bytes.
+    /// @param index Index of nested bytes.
+    /// @return result Nested bytes.
+    function publicReadBytesWithLength(
+        bytes memory b,
+        uint256 index
+    )
+        public
+        pure
+        returns (bytes memory result)
+    {
+        result = b.readBytesWithLength(index);
+        return result;
+    }
+
+    /// @dev Inserts bytes at a specific position in a byte array.
+    /// @param b Byte array to insert <input> into.
+    /// @param index Index in byte array of <input>.
+    /// @param input bytes to insert.
+    /// @return b Updated input byte array
+    function publicWriteBytesWithLength(
+        bytes memory b,
+        uint256 index,
+        bytes memory input
+    )
+        public
+        pure
+        returns (bytes memory)
+    {
+        b.writeBytesWithLength(index, input);
+        return b;
+    }
+    
+    /// @dev Copies a block of memory from one location to another.
+    /// @param mem Memory contents we want to apply memCopy to
+    /// @param dest Destination offset into <mem>.
+    /// @param source Source offset into <mem>.
+    /// @param length Length of bytes to copy from <source> to <dest>
+    /// @return mem Memory contents after calling memCopy.
+    function testMemcpy(
+        bytes mem,
+        uint256 dest,
+        uint256 source,
+        uint256 length
+    )
+        public // not external, we need input in memory
+        pure
+        returns (bytes)
+    {
+        // Sanity check. Overflows are not checked.
+        require(source + length <= mem.length);
+        require(dest + length <= mem.length);
+
+        // Get pointer to memory contents
+        uint256 offset = mem.contentAddress();
+
+        // Execute memCopy adjusted for memory array location
+        LibBytes.memCopy(offset + dest, offset + source, length);
+
+        // Return modified memory contents
+        return mem;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/test/TestLibs/TestLibs.sol b/packages/contracts/src/2.0.0/test/TestLibs/TestLibs.sol
new file mode 100644
index 000000000..010080703
--- /dev/null
+++ b/packages/contracts/src/2.0.0/test/TestLibs/TestLibs.sol
@@ -0,0 +1,96 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../protocol/Exchange/libs/LibMath.sol";
+import "../../protocol/Exchange/libs/LibOrder.sol";
+import "../../protocol/Exchange/libs/LibFillResults.sol";
+
+contract TestLibs is 
+    LibMath,
+    LibOrder,
+    LibFillResults
+{
+    function publicGetPartialAmount(
+        uint256 numerator,
+        uint256 denominator,
+        uint256 target)
+        public
+        pure
+        returns (uint256 partialAmount)
+    {
+        partialAmount = getPartialAmount(
+            numerator,
+            denominator,
+            target
+        );
+        return partialAmount;
+    }
+
+    function publicIsRoundingError(
+        uint256 numerator,
+        uint256 denominator,
+        uint256 target)
+        public
+        pure
+        returns (bool isError)
+    {
+        isError = isRoundingError(
+            numerator,
+            denominator,
+            target
+        );
+        return isError;
+    }
+
+    function publicGetOrderHash(Order memory order)
+        public
+        view
+        returns (bytes32 orderHash)
+    {
+        orderHash = getOrderHash(order);
+        return orderHash;
+    }
+
+    function getOrderSchemaHash()
+        public
+        pure
+        returns (bytes32)
+    {
+        return EIP712_ORDER_SCHEMA_HASH;
+    }
+
+    function getDomainSeparatorSchemaHash()
+        public
+        pure
+        returns (bytes32)
+    {
+        return EIP712_DOMAIN_SEPARATOR_SCHEMA_HASH;
+    }
+
+    function publicAddFillResults(FillResults memory totalFillResults, FillResults memory singleFillResults)
+        public
+        pure
+        returns (FillResults memory)
+    {
+        addFillResults(totalFillResults, singleFillResults);
+        return totalFillResults;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/test/TestSignatureValidator/TestSignatureValidator.sol b/packages/contracts/src/2.0.0/test/TestSignatureValidator/TestSignatureValidator.sol
new file mode 100644
index 000000000..0f84678cf
--- /dev/null
+++ b/packages/contracts/src/2.0.0/test/TestSignatureValidator/TestSignatureValidator.sol
@@ -0,0 +1,46 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../protocol/Exchange/MixinSignatureValidator.sol";
+import "../../protocol/Exchange/MixinTransactions.sol";
+
+contract TestSignatureValidator is
+    MixinSignatureValidator,
+    MixinTransactions
+{
+
+    function publicIsValidSignature(
+        bytes32 hash,
+        address signer,
+        bytes memory signature
+    )
+        public
+        view
+        returns (bool isValid)
+    {
+        isValid = isValidSignature(
+            hash,
+            signer,
+            signature
+        );
+        return isValid;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/test/TestValidator/TestValidator.sol b/packages/contracts/src/2.0.0/test/TestValidator/TestValidator.sol
new file mode 100644
index 000000000..f9271bf7a
--- /dev/null
+++ b/packages/contracts/src/2.0.0/test/TestValidator/TestValidator.sol
@@ -0,0 +1,52 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+import "../../protocol/Exchange/interfaces/IValidator.sol";
+
+contract TestValidator is 
+    IValidator
+{
+
+    // The single valid signer for this wallet.
+    address VALID_SIGNER;
+
+    /// @dev constructs a new `TestValidator` with a single valid signer.
+    /// @param validSigner The sole, valid signer.
+    constructor (address validSigner) public {
+        VALID_SIGNER = validSigner;
+    }
+
+    /// @dev Verifies that a signature is valid. `signer` must match `VALID_SIGNER`.
+    /// @param hash Message hash that is signed.
+    /// @param signerAddress Address that should have signed the given hash.
+    /// @param signature Proof of signing.
+    /// @return Validity of signature.
+    function isValidSignature(
+        bytes32 hash,
+        address signerAddress,
+        bytes signature
+    )
+        external
+        view
+        returns (bool isValid)
+    {
+        return (signerAddress == VALID_SIGNER);
+    }
+}
diff --git a/packages/contracts/src/2.0.0/test/TestWallet/TestWallet.sol b/packages/contracts/src/2.0.0/test/TestWallet/TestWallet.sol
new file mode 100644
index 000000000..17dee9e9c
--- /dev/null
+++ b/packages/contracts/src/2.0.0/test/TestWallet/TestWallet.sol
@@ -0,0 +1,65 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+import "../../protocol/Exchange/interfaces/IWallet.sol";
+import "../../utils/LibBytes/LibBytes.sol";
+
+contract TestWallet is 
+    IWallet
+{
+    using LibBytes for bytes;
+
+    string constant LENGTH_65_REQUIRED = "LENGTH_65_REQUIRED";
+
+    // The owner of this wallet.
+    address WALLET_OWNER;
+
+    /// @dev constructs a new `TestWallet` with a single owner.
+    /// @param walletOwner The owner of this wallet.
+    constructor (address walletOwner) public {
+        WALLET_OWNER = walletOwner;
+    }
+
+    /// @dev Validates an EIP712 signature.
+    ///      The signer must match the owner of this wallet.
+    /// @param hash Message hash that is signed.
+    /// @param eip712Signature Proof of signing.
+    /// @return Validity of signature.
+    function isValidSignature(
+        bytes32 hash,
+        bytes eip712Signature
+    )
+        external
+        view
+        returns (bool isValid)
+    {
+        require(
+            eip712Signature.length == 65,
+            LENGTH_65_REQUIRED
+        );
+
+        uint8 v = uint8(eip712Signature[0]);
+        bytes32 r = eip712Signature.readBytes32(1);
+        bytes32 s = eip712Signature.readBytes32(33);
+        address recoveredAddress = ecrecover(hash, v, r, s);
+        isValid = WALLET_OWNER == recoveredAddress;
+        return isValid;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/test/Whitelist/Whitelist.sol b/packages/contracts/src/2.0.0/test/Whitelist/Whitelist.sol
new file mode 100644
index 000000000..8b52858b1
--- /dev/null
+++ b/packages/contracts/src/2.0.0/test/Whitelist/Whitelist.sol
@@ -0,0 +1,133 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../protocol/Exchange/interfaces/IExchange.sol";
+import "../../protocol/Exchange/libs/LibOrder.sol";
+import "../../utils/Ownable/Ownable.sol";
+
+contract Whitelist is
+    Ownable
+{
+    // Revert reasons
+    string constant MAKER_NOT_WHITELISTED = "MAKER_NOT_WHITELISTED"; // Maker address not whitelisted.
+    string constant TAKER_NOT_WHITELISTED = "TAKER_NOT_WHITELISTED"; // Taker address not whitelisted.
+    string constant INVALID_SENDER = "INVALID_SENDER"; // Sender must equal transaction origin.
+
+    // Mapping of address => whitelist status.
+    mapping (address => bool) public isWhitelisted;
+
+    // Exchange contract.
+    IExchange EXCHANGE;
+
+    byte constant VALIDATOR_SIGNATURE_BYTE = "\x06";
+    bytes TX_ORIGIN_SIGNATURE;
+
+    constructor (address _exchange)
+        public
+    {
+        EXCHANGE = IExchange(_exchange);
+        TX_ORIGIN_SIGNATURE = abi.encodePacked(address(this), VALIDATOR_SIGNATURE_BYTE);
+    }
+
+    /// @dev Adds or removes an address from the whitelist.
+    /// @param target Address to add or remove from whitelist.
+    /// @param isApproved Whitelist status to assign to address.
+    function updateWhitelistStatus(
+        address target,
+        bool isApproved
+    )
+        external
+        onlyOwner
+    {
+        isWhitelisted[target] = isApproved;
+    }
+
+    /// @dev Fills an order using `msg.sender` as the taker.
+    ///      The transaction will revert if both the maker and taker are not whitelisted.
+    ///      Orders should specify this contract as the `senderAddress` in order to gaurantee
+    ///      that both maker and taker have been whitelisted.
+    /// @param order Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param salt Arbitrary value to gaurantee uniqueness of 0x transaction hash.
+    /// @param orderSignature Proof that order has been created by maker.
+    function fillOrderIfWhitelisted(
+        LibOrder.Order memory order,
+        uint256 takerAssetFillAmount,
+        uint256 salt,
+        bytes memory orderSignature
+    )
+        public
+    {
+        address takerAddress = msg.sender;
+
+        // This contract must be the entry point for the transaction.
+        require(
+            takerAddress == tx.origin,
+            INVALID_SENDER
+        );
+
+        // Check if maker is on the whitelist.
+        require(
+            isWhitelisted[order.makerAddress],
+            MAKER_NOT_WHITELISTED
+        );
+
+        // Check if taker is on the whitelist.
+        require(
+            isWhitelisted[takerAddress],
+            TAKER_NOT_WHITELISTED
+        );
+
+        // Encode arguments into byte array.
+        bytes memory data = abi.encodeWithSelector(
+            EXCHANGE.fillOrder.selector,
+            order,
+            takerAssetFillAmount,
+            orderSignature
+        );
+
+        // Call `fillOrder` via `executeTransaction`.
+        EXCHANGE.executeTransaction(
+            salt,
+            takerAddress,
+            data,
+            TX_ORIGIN_SIGNATURE
+        );
+    }
+
+    /// @dev Verifies signer is same as signer of current Ethereum transaction.
+    ///      NOTE: This function can currently be used to validate signatures coming from outside of this contract.
+    ///      Extra safety checks can be added for a production contract.
+    /// @param signerAddress Address that should have signed the given hash.
+    /// @param signature Proof of signing.
+    /// @return Validity of order signature.
+    function isValidSignature(
+        bytes32 hash,
+        address signerAddress,
+        bytes signature
+    )
+        external
+        view
+        returns (bool isValid)
+    {
+        return signerAddress == tx.origin;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/tokens/ERC20Token/ERC20Token.sol b/packages/contracts/src/2.0.0/tokens/ERC20Token/ERC20Token.sol
new file mode 100644
index 000000000..b6961a6ec
--- /dev/null
+++ b/packages/contracts/src/2.0.0/tokens/ERC20Token/ERC20Token.sol
@@ -0,0 +1,99 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./IERC20Token.sol";
+
+contract ERC20Token is IERC20Token {
+
+    string constant INSUFFICIENT_BALANCE = "ERC20_INSUFFICIENT_BALANCE";
+    string constant INSUFFICIENT_ALLOWANCE = "ERC20_INSUFFICIENT_ALLOWANCE";
+    string constant OVERFLOW = "Transfer would result in an overflow.";
+
+    mapping (address => uint256) balances;
+    mapping (address => mapping (address => uint256)) allowed;
+
+    uint256 public totalSupply;
+
+    function transfer(address _to, uint256 _value)
+        public
+        returns (bool)
+    {
+        require(
+            balances[msg.sender] >= _value,
+            INSUFFICIENT_BALANCE
+        );
+        require(
+            balances[_to] + _value >= balances[_to],
+            OVERFLOW
+        );
+        balances[msg.sender] -= _value;
+        balances[_to] += _value;
+        emit Transfer(msg.sender, _to, _value);
+        return true;
+    }
+
+    function transferFrom(address _from, address _to, uint256 _value)
+        public
+        returns (bool)
+    {
+        require(
+            balances[_from] >= _value,
+            INSUFFICIENT_BALANCE
+        );
+        require(
+            allowed[_from][msg.sender] >= _value,
+            INSUFFICIENT_ALLOWANCE
+        );
+        require(
+            balances[_to] + _value >= balances[_to],
+            OVERFLOW
+        );
+        balances[_to] += _value;
+        balances[_from] -= _value;
+        allowed[_from][msg.sender] -= _value;
+        emit Transfer(_from, _to, _value);
+        return true;
+    }
+
+    function approve(address _spender, uint256 _value)
+        public
+        returns (bool)
+    {
+        allowed[msg.sender][_spender] = _value;
+        emit Approval(msg.sender, _spender, _value);
+        return true;
+    }
+
+    function balanceOf(address _owner)
+        public view
+        returns (uint256)
+    {
+        return balances[_owner];
+    }
+
+    function allowance(address _owner, address _spender)
+        public
+        view
+        returns (uint256)
+    {
+        return allowed[_owner][_spender];
+    }
+}
diff --git a/packages/contracts/src/2.0.0/tokens/ERC20Token/IERC20Token.sol b/packages/contracts/src/2.0.0/tokens/ERC20Token/IERC20Token.sol
new file mode 100644
index 000000000..eb879b6a8
--- /dev/null
+++ b/packages/contracts/src/2.0.0/tokens/ERC20Token/IERC20Token.sol
@@ -0,0 +1,73 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+contract IERC20Token {
+
+    /// @notice send `value` token to `to` from `msg.sender`
+    /// @param _to The address of the recipient
+    /// @param _value The amount of token to be transferred
+    /// @return Whether the transfer was successful or not
+    function transfer(address _to, uint256 _value)
+        public
+        returns (bool);
+
+    /// @notice send `value` token to `to` from `from` on the condition it is approved by `from`
+    /// @param _from The address of the sender
+    /// @param _to The address of the recipient
+    /// @param _value The amount of token to be transferred
+    /// @return Whether the transfer was successful or not
+    function transferFrom(address _from, address _to, uint256 _value)
+        public
+        returns (bool);
+    
+    /// @notice `msg.sender` approves `_spender` to spend `_value` tokens
+    /// @param _spender The address of the account able to transfer the tokens
+    /// @param _value The amount of wei to be approved for transfer
+    /// @return Whether the approval was successful or not
+    function approve(address _spender, uint256 _value)
+        public
+        returns (bool);
+
+    /// @param _owner The address from which the balance will be retrieved
+    /// @return The balance
+    function balanceOf(address _owner)
+        public view
+        returns (uint256);
+
+    /// @param _owner The address of the account owning tokens
+    /// @param _spender The address of the account able to transfer the tokens
+    /// @return Amount of remaining tokens allowed to spent
+    function allowance(address _owner, address _spender)
+        public view
+        returns (uint256);
+
+    event Transfer(
+        address indexed _from,
+        address indexed _to,
+        uint256 _value
+    );
+    
+    event Approval(
+        address indexed _owner,
+        address indexed _spender,
+        uint256 _value
+    );
+}
diff --git a/packages/contracts/src/2.0.0/tokens/ERC721Token/ERC721Token.sol b/packages/contracts/src/2.0.0/tokens/ERC721Token/ERC721Token.sol
new file mode 100644
index 000000000..41ba149e3
--- /dev/null
+++ b/packages/contracts/src/2.0.0/tokens/ERC721Token/ERC721Token.sol
@@ -0,0 +1,406 @@
+/*
+The MIT License (MIT)
+
+Copyright (c) 2016 Smart Contract Solutions, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+pragma solidity ^0.4.24;
+
+import "./IERC721Token.sol";
+import "./IERC721Receiver.sol";
+import "../../utils/SafeMath/SafeMath.sol";
+
+/**
+ * @title ERC721 Non-Fungible Token Standard basic implementation
+ * @dev see https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
+ * Modified from https://github.com/OpenZeppelin/zeppelin-solidity/blob/master/contracts/token/ERC721/ERC721BasicToken.sol
+ */
+contract ERC721Token is
+    IERC721Token,
+    SafeMath
+{
+    // Equals to `bytes4(keccak256("onERC721Received(address,uint256,bytes)"))`
+    // which can be also obtained as `ERC721Receiver(0).onERC721Received.selector`
+    bytes4 constant ERC721_RECEIVED = 0xf0b9e5ba;
+
+    // Mapping from token ID to owner
+    mapping (uint256 => address) internal tokenOwner;
+
+    // Mapping from token ID to approved address
+    mapping (uint256 => address) internal tokenApprovals;
+
+    // Mapping from owner to number of owned token
+    mapping (address => uint256) internal ownedTokensCount;
+
+    // Mapping from owner to operator approvals
+    mapping (address => mapping (address => bool)) internal operatorApprovals;
+
+    /**
+    * @dev Guarantees msg.sender is owner of the given token
+    * @param _tokenId uint256 ID of the token to validate its ownership belongs to msg.sender
+    */
+    modifier onlyOwnerOf(uint256 _tokenId) {
+        require(ownerOf(_tokenId) == msg.sender);
+        _;
+    }
+
+    /**
+    * @dev Checks msg.sender can transfer a token, by being owner, approved, or operator
+    * @param _tokenId uint256 ID of the token to validate
+    */
+    modifier canTransfer(uint256 _tokenId) {
+        require(isApprovedOrOwner(msg.sender, _tokenId));
+        _;
+    }
+
+    function ERC721Token(
+        string _name,
+        string _symbol)
+        public
+    {
+        name_ = _name;
+        symbol_ = _symbol;
+    }
+
+    /**
+    * @dev Gets the token name
+    * @return string representing the token name
+    */
+    function name()
+        public
+        view
+        returns (string)
+    {
+        return name_;
+    }
+
+    /**
+    * @dev Gets the token symbol
+    * @return string representing the token symbol
+    */
+    function symbol()
+        public
+        view
+        returns (string)
+    {
+        return symbol_;
+    }
+
+    /**
+    * @dev Gets the balance of the specified address
+    * @param _owner address to query the balance of
+    * @return uint256 representing the amount owned by the passed address
+    */
+    function balanceOf(address _owner)
+        public
+        view
+        returns (uint256)
+    {
+        require(_owner != address(0));
+        return ownedTokensCount[_owner];
+    }
+
+    /**
+    * @dev Gets the owner of the specified token ID
+    * @param _tokenId uint256 ID of the token to query the owner of
+    * @return owner address currently marked as the owner of the given token ID
+    */
+    function ownerOf(uint256 _tokenId)
+        public
+        view
+        returns (address)
+    {
+        address owner = tokenOwner[_tokenId];
+        require(owner != address(0));
+        return owner;
+    }
+
+    /**
+    * @dev Returns whether the specified token exists
+    * @param _tokenId uint256 ID of the token to query the existance of
+    * @return whether the token exists
+    */
+    function exists(uint256 _tokenId)
+        public
+        view
+        returns (bool)
+    {
+        address owner = tokenOwner[_tokenId];
+        return owner != address(0);
+    }
+
+    /**
+    * @dev Approves another address to transfer the given token ID
+    * @dev The zero address indicates there is no approved address.
+    * @dev There can only be one approved address per token at a given time.
+    * @dev Can only be called by the token owner or an approved operator.
+    * @param _to address to be approved for the given token ID
+    * @param _tokenId uint256 ID of the token to be approved
+    */
+    function approve(address _to, uint256 _tokenId)
+        public
+    {
+        address owner = ownerOf(_tokenId);
+        require(_to != owner);
+        require(msg.sender == owner || isApprovedForAll(owner, msg.sender));
+
+        if (getApproved(_tokenId) != address(0) || _to != address(0)) {
+            tokenApprovals[_tokenId] = _to;
+            emit Approval(owner, _to, _tokenId);
+        }
+    }
+
+    /**
+    * @dev Gets the approved address for a token ID, or zero if no address set
+    * @param _tokenId uint256 ID of the token to query the approval of
+    * @return address currently approved for a the given token ID
+    */
+    function getApproved(uint256 _tokenId)
+        public
+        view
+        returns (address)
+    {
+        return tokenApprovals[_tokenId];
+    }
+
+    /**
+    * @dev Sets or unsets the approval of a given operator
+    * @dev An operator is allowed to transfer all tokens of the sender on their behalf
+    * @param _to operator address to set the approval
+    * @param _approved representing the status of the approval to be set
+    */
+    function setApprovalForAll(address _to, bool _approved)
+        public
+    {
+        require(_to != msg.sender);
+        operatorApprovals[msg.sender][_to] = _approved;
+        emit ApprovalForAll(msg.sender, _to, _approved);
+    }
+
+    /**
+    * @dev Tells whether an operator is approved by a given owner
+    * @param _owner owner address which you want to query the approval of
+    * @param _operator operator address which you want to query the approval of
+    * @return bool whether the given operator is approved by the given owner
+    */
+    function isApprovedForAll(address _owner, address _operator)
+        public
+        view
+        returns (bool)
+    {
+        return operatorApprovals[_owner][_operator];
+    }
+
+    /**
+    * @dev Transfers the ownership of a given token ID to another address
+    * @dev Usage of this method is discouraged, use `safeTransferFrom` whenever possible
+    * @dev Requires the msg sender to be the owner, approved, or operator
+    * @param _from current owner of the token
+    * @param _to address to receive the ownership of the given token ID
+    * @param _tokenId uint256 ID of the token to be transferred
+    */
+    function transferFrom(address _from, address _to, uint256 _tokenId)
+        public
+        canTransfer(_tokenId)
+    {
+        require(_from != address(0));
+        require(_to != address(0));
+
+        clearApproval(_from, _tokenId);
+        removeTokenFrom(_from, _tokenId);
+        addTokenTo(_to, _tokenId);
+
+        emit Transfer(_from, _to, _tokenId);
+    }
+
+    /**
+    * @dev Safely transfers the ownership of a given token ID to another address
+    * @dev If the target address is a contract, it must implement `onERC721Received`,
+    *  which is called upon a safe transfer, and return the magic value
+    *  `bytes4(keccak256("onERC721Received(address,uint256,bytes)"))`; otherwise,
+    *  the transfer is reverted.
+    * @dev Requires the msg sender to be the owner, approved, or operator
+    * @param _from current owner of the token
+    * @param _to address to receive the ownership of the given token ID
+    * @param _tokenId uint256 ID of the token to be transferred
+    */
+    function safeTransferFrom(
+        address _from,
+        address _to,
+        uint256 _tokenId)
+        public
+        canTransfer(_tokenId)
+    {
+        // solium-disable-next-line arg-overflow
+        safeTransferFrom(_from, _to, _tokenId, "");
+    }
+
+    /**
+    * @dev Safely transfers the ownership of a given token ID to another address
+    * @dev If the target address is a contract, it must implement `onERC721Received`,
+    *  which is called upon a safe transfer, and return the magic value
+    *  `bytes4(keccak256("onERC721Received(address,uint256,bytes)"))`; otherwise,
+    *  the transfer is reverted.
+    * @dev Requires the msg sender to be the owner, approved, or operator
+    * @param _from current owner of the token
+    * @param _to address to receive the ownership of the given token ID
+    * @param _tokenId uint256 ID of the token to be transferred
+    * @param _data bytes data to send along with a safe transfer check
+    */
+    function safeTransferFrom(
+        address _from,
+        address _to,
+        uint256 _tokenId,
+        bytes _data)
+        public
+        canTransfer(_tokenId)
+    {
+        transferFrom(_from, _to, _tokenId);
+        // solium-disable-next-line arg-overflow
+        require(checkAndCallSafeTransfer(_from, _to, _tokenId, _data));
+    }
+
+    /**
+    * @dev Returns whether the given spender can transfer a given token ID
+    * @param _spender address of the spender to query
+    * @param _tokenId uint256 ID of the token to be transferred
+    * @return bool whether the msg.sender is approved for the given token ID,
+    *  is an operator of the owner, or is the owner of the token
+    */
+    function isApprovedOrOwner(address _spender, uint256 _tokenId)
+        internal
+        view
+        returns (bool)
+    {
+        address owner = ownerOf(_tokenId);
+        return _spender == owner || getApproved(_tokenId) == _spender || isApprovedForAll(owner, _spender);
+    }
+
+    /**
+    * @dev Internal function to mint a new token
+    * @dev Reverts if the given token ID already exists
+    * @param _to The address that will own the minted token
+    * @param _tokenId uint256 ID of the token to be minted by the msg.sender
+    */
+    function _mint(address _to, uint256 _tokenId)
+        internal
+    {
+        require(_to != address(0));
+        addTokenTo(_to, _tokenId);
+        emit Transfer(address(0), _to, _tokenId);
+    }
+
+    /**
+    * @dev Internal function to burn a specific token
+    * @dev Reverts if the token does not exist
+    * @param _tokenId uint256 ID of the token being burned by the msg.sender
+    */
+    function _burn(address _owner, uint256 _tokenId)
+        internal
+    {
+        clearApproval(_owner, _tokenId);
+        removeTokenFrom(_owner, _tokenId);
+        emit Transfer(_owner, address(0), _tokenId);
+    }
+
+    /**
+    * @dev Internal function to clear current approval of a given token ID
+    * @dev Reverts if the given address is not indeed the owner of the token
+    * @param _owner owner of the token
+    * @param _tokenId uint256 ID of the token to be transferred
+    */
+    function clearApproval(address _owner, uint256 _tokenId)
+        internal
+    {
+        require(ownerOf(_tokenId) == _owner);
+        if (tokenApprovals[_tokenId] != address(0)) {
+            tokenApprovals[_tokenId] = address(0);
+            emit Approval(_owner, address(0), _tokenId);
+        }
+    }
+
+    /**
+    * @dev Internal function to add a token ID to the list of a given address
+    * @param _to address representing the new owner of the given token ID
+    * @param _tokenId uint256 ID of the token to be added to the tokens list of the given address
+    */
+    function addTokenTo(address _to, uint256 _tokenId)
+        internal
+    {
+        require(tokenOwner[_tokenId] == address(0));
+        tokenOwner[_tokenId] = _to;
+        ownedTokensCount[_to] = safeAdd(ownedTokensCount[_to], 1);
+    }
+
+    /**
+    * @dev Internal function to remove a token ID from the list of a given address
+    * @param _from address representing the previous owner of the given token ID
+    * @param _tokenId uint256 ID of the token to be removed from the tokens list of the given address
+    */
+    function removeTokenFrom(address _from, uint256 _tokenId)
+        internal
+    {
+        require(ownerOf(_tokenId) == _from);
+        ownedTokensCount[_from] = safeSub(ownedTokensCount[_from], 1);
+        tokenOwner[_tokenId] = address(0);
+    }
+
+    /**
+    * @dev Internal function to invoke `onERC721Received` on a target address
+    * @dev The call is not executed if the target address is not a contract
+    * @param _from address representing the previous owner of the given token ID
+    * @param _to target address that will receive the tokens
+    * @param _tokenId uint256 ID of the token to be transferred
+    * @param _data bytes optional data to send along with the call
+    * @return whether the call correctly returned the expected magic value
+    */
+    function checkAndCallSafeTransfer(
+        address _from,
+        address _to,
+        uint256 _tokenId,
+        bytes _data)
+        internal
+        returns (bool)
+    {
+        if (!isContract(_to)) {
+            return true;
+        }
+        bytes4 retval = IERC721Receiver(_to).onERC721Received(_from, _tokenId, _data);
+        return (retval == ERC721_RECEIVED);
+    }
+
+    function isContract(address addr)
+        internal
+        view
+        returns (bool)
+    {
+        uint256 size;
+        // XXX Currently there is no better way to check if there is a contract in an address
+        // than to check the size of the code at that address.
+        // See https://ethereum.stackexchange.com/a/14016/36603
+        // for more details about how this works.
+        // TODO Check this again before the Serenity release, because all addresses will be
+        // contracts then.
+        assembly { size := extcodesize(addr) }  // solium-disable-line security/no-inline-assembly
+        return size > 0;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/tokens/ERC721Token/IERC721Receiver.sol b/packages/contracts/src/2.0.0/tokens/ERC721Token/IERC721Receiver.sol
new file mode 100644
index 000000000..b0fff3c90
--- /dev/null
+++ b/packages/contracts/src/2.0.0/tokens/ERC721Token/IERC721Receiver.sol
@@ -0,0 +1,60 @@
+/*
+The MIT License (MIT)
+
+Copyright (c) 2016 Smart Contract Solutions, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+pragma solidity ^0.4.24;
+
+/**
+ * @title ERC721 token receiver interface
+ * @dev Interface for any contract that wants to support safeTransfers
+ *      rom ERC721 asset contracts.
+ * Modified from https://github.com/OpenZeppelin/zeppelin-solidity/blob/master/contracts/token/ERC721/ERC721Receiver.sol
+ */
+contract IERC721Receiver {
+    /**
+    * @dev Magic value to be returned upon successful reception of an NFT
+    *  Equals to `bytes4(keccak256("onERC721Received(address,uint256,bytes)"))`,
+    *  which can be also obtained as `ERC721Receiver(0).onERC721Received.selector`
+    */
+    bytes4 constant ERC721_RECEIVED = 0xf0b9e5ba;
+
+    /**
+    * @notice Handle the receipt of an NFT
+    * @dev The ERC721 smart contract calls this function on the recipient
+    *  after a `safetransfer`. This function MAY throw to revert and reject the
+    *  transfer. This function MUST use 50,000 gas or less. Return of other
+    *  than the magic value MUST result in the transaction being reverted.
+    *  Note: the contract address is always the message sender.
+    * @param _from The sending address
+    * @param _tokenId The NFT identifier which is being transfered
+    * @param _data Additional data with no specified format
+    * @return `bytes4(keccak256("onERC721Received(address,uint256,bytes)"))`
+    */
+    function onERC721Received(
+        address _from,
+        uint256 _tokenId,
+        bytes _data)
+        public
+        returns (bytes4);
+}
diff --git a/packages/contracts/src/2.0.0/tokens/ERC721Token/IERC721Token.sol b/packages/contracts/src/2.0.0/tokens/ERC721Token/IERC721Token.sol
new file mode 100644
index 000000000..345712d67
--- /dev/null
+++ b/packages/contracts/src/2.0.0/tokens/ERC721Token/IERC721Token.sol
@@ -0,0 +1,105 @@
+/*
+The MIT License (MIT)
+
+Copyright (c) 2016 Smart Contract Solutions, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+pragma solidity ^0.4.24;
+
+/**
+ * @title ERC721 Non-Fungible Token Standard basic interface
+ * @dev see https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
+ * Modified from https://github.com/OpenZeppelin/zeppelin-solidity/blob/master/contracts/token/ERC721/ERC721Basic.sol
+ */
+contract IERC721Token {
+    string internal name_;
+    string internal symbol_;
+
+    event Transfer(
+        address indexed _from,
+        address indexed _to,
+        uint256 _tokenId
+    );
+    event Approval(
+        address indexed _owner,
+        address indexed _approved,
+        uint256 _tokenId
+    );
+    event ApprovalForAll(
+        address indexed _owner,
+        address indexed _operator,
+        bool _approved
+    );
+
+    function name()
+        public
+        view
+        returns (string);
+    function symbol()
+        public
+        view
+        returns (string);
+
+    function balanceOf(address _owner)
+        public
+        view
+        returns (uint256 _balance);
+    function ownerOf(uint256 _tokenId)
+        public
+        view
+        returns (address _owner);
+    function exists(uint256 _tokenId)
+        public
+        view
+        returns (bool _exists);
+
+    function approve(address _to, uint256 _tokenId)
+        public;
+    function getApproved(uint256 _tokenId)
+        public
+        view
+        returns (address _operator);
+
+    function setApprovalForAll(address _operator, bool _approved)
+        public;
+    function isApprovedForAll(address _owner, address _operator)
+        public
+        view
+        returns (bool);
+
+    function transferFrom(
+        address _from,
+        address _to,
+        uint256 _tokenId)
+        public;
+    function safeTransferFrom(
+        address _from,
+        address _to,
+        uint256 _tokenId)
+        public;
+    function safeTransferFrom(
+        address _from,
+        address _to,
+        uint256 _tokenId,
+        bytes _data)
+        public;
+}
diff --git a/packages/contracts/src/2.0.0/tokens/UnlimitedAllowanceToken/UnlimitedAllowanceToken.sol b/packages/contracts/src/2.0.0/tokens/UnlimitedAllowanceToken/UnlimitedAllowanceToken.sol
new file mode 100644
index 000000000..f62602ab3
--- /dev/null
+++ b/packages/contracts/src/2.0.0/tokens/UnlimitedAllowanceToken/UnlimitedAllowanceToken.sol
@@ -0,0 +1,58 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../ERC20Token/ERC20Token.sol";
+
+contract UnlimitedAllowanceToken is ERC20Token {
+
+    uint256 constant MAX_UINT = 2**256 - 1;
+
+    /// @dev ERC20 transferFrom, modified such that an allowance of MAX_UINT represents an unlimited allowance. See https://github.com/ethereum/EIPs/issues/717
+    /// @param _from Address to transfer from.
+    /// @param _to Address to transfer to.
+    /// @param _value Amount to transfer.
+    /// @return Success of transfer.
+    function transferFrom(address _from, address _to, uint256 _value)
+        public
+        returns (bool)
+    {
+        uint256 allowance = allowed[_from][msg.sender];
+        require(
+            balances[_from] >= _value,
+            INSUFFICIENT_BALANCE
+        );
+        require(
+            allowance >= _value,
+            INSUFFICIENT_ALLOWANCE
+        );
+        require(
+            balances[_to] + _value >= balances[_to],
+            OVERFLOW
+        );
+        balances[_to] += _value;
+        balances[_from] -= _value;
+        if (allowance < MAX_UINT) {
+            allowed[_from][msg.sender] -= _value;
+        }
+        emit Transfer(_from, _to, _value);
+        return true;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/tokens/WETH9/WETH9.sol b/packages/contracts/src/2.0.0/tokens/WETH9/WETH9.sol
new file mode 100644
index 000000000..733ca414b
--- /dev/null
+++ b/packages/contracts/src/2.0.0/tokens/WETH9/WETH9.sol
@@ -0,0 +1,756 @@
+// Copyright (C) 2015, 2016, 2017 Dapphub
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+pragma solidity ^0.4.18;
+
+contract WETH9 {
+    string public name     = "Wrapped Ether";
+    string public symbol   = "WETH";
+    uint8  public decimals = 18;
+
+    event  Approval(address indexed src, address indexed guy, uint wad);
+    event  Transfer(address indexed src, address indexed dst, uint wad);
+    event  Deposit(address indexed dst, uint wad);
+    event  Withdrawal(address indexed src, uint wad);
+
+    mapping (address => uint)                       public  balanceOf;
+    mapping (address => mapping (address => uint))  public  allowance;
+
+    function() public payable {
+        deposit();
+    }
+    function deposit() public payable {
+        balanceOf[msg.sender] += msg.value;
+        Deposit(msg.sender, msg.value);
+    }
+    function withdraw(uint wad) public {
+        require(balanceOf[msg.sender] >= wad);
+        balanceOf[msg.sender] -= wad;
+        msg.sender.transfer(wad);
+        Withdrawal(msg.sender, wad);
+    }
+
+    function totalSupply() public view returns (uint) {
+        return this.balance;
+    }
+
+    function approve(address guy, uint wad) public returns (bool) {
+        allowance[msg.sender][guy] = wad;
+        Approval(msg.sender, guy, wad);
+        return true;
+    }
+
+    function transfer(address dst, uint wad) public returns (bool) {
+        return transferFrom(msg.sender, dst, wad);
+    }
+
+    function transferFrom(address src, address dst, uint wad)
+        public
+        returns (bool)
+    {
+        require(balanceOf[src] >= wad);
+
+        if (src != msg.sender && allowance[src][msg.sender] != uint(-1)) {
+            require(allowance[src][msg.sender] >= wad);
+            allowance[src][msg.sender] -= wad;
+        }
+
+        balanceOf[src] -= wad;
+        balanceOf[dst] += wad;
+
+        Transfer(src, dst, wad);
+
+        return true;
+    }
+}
+
+
+/*
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The GNU General Public License is a free, copyleft license for
+software and other kinds of works.
+
+  The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works.  By contrast,
+the GNU General Public License is intended to guarantee your freedom to
+share and change all versions of a program--to make sure it remains free
+software for all its users.  We, the Free Software Foundation, use the
+GNU General Public License for most of our software; it applies also to
+any other work released this way by its authors.  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+them if you wish), that you receive source code or can get it if you
+want it, that you can change the software or use pieces of it in new
+free programs, and that you know you can do these things.
+
+  To protect your rights, we need to prevent others from denying you
+these rights or asking you to surrender the rights.  Therefore, you have
+certain responsibilities if you distribute copies of the software, or if
+you modify it: responsibilities to respect the freedom of others.
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+  For example, if you distribute copies of such a program, whether
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+know their rights.
+
+  Developers that use the GNU GPL protect your rights with two steps:
+(1) assert copyright on the software, and (2) offer you this License
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+  For the developers' and authors' protection, the GPL clearly explains
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+  The precise terms and conditions for copying, distribution and
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+    but WITHOUT ANY WARRANTY; without even the implied warranty of
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+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<http://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<http://www.gnu.org/philosophy/why-not-lgpl.html>.
+
+*/
diff --git a/packages/contracts/src/2.0.0/tokens/ZRXToken/ZRXToken.sol b/packages/contracts/src/2.0.0/tokens/ZRXToken/ZRXToken.sol
new file mode 100644
index 000000000..2e5b61e0b
--- /dev/null
+++ b/packages/contracts/src/2.0.0/tokens/ZRXToken/ZRXToken.sol
@@ -0,0 +1,33 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.11;
+
+import { UnlimitedAllowanceToken_v1 as UnlimitedAllowanceToken } from "../../../1.0.0/UnlimitedAllowanceToken/UnlimitedAllowanceToken_v1.sol";
+
+contract ZRXToken is UnlimitedAllowanceToken {
+
+    uint8 constant public decimals = 18;
+    uint public totalSupply = 10**27; // 1 billion tokens, 18 decimal places
+    string constant public name = "0x Protocol Token";
+    string constant public symbol = "ZRX";
+
+    function ZRXToken() {
+        balances[msg.sender] = totalSupply;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/utils/LibBytes/LibBytes.sol b/packages/contracts/src/2.0.0/utils/LibBytes/LibBytes.sol
new file mode 100644
index 000000000..78b1ddf7c
--- /dev/null
+++ b/packages/contracts/src/2.0.0/utils/LibBytes/LibBytes.sol
@@ -0,0 +1,545 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+
+library LibBytes {
+
+    using LibBytes for bytes;
+
+    /// @dev Gets the memory address for a byte array.
+    /// @param input Byte array to lookup.
+    /// @return memoryAddress Memory address of byte array. This
+    ///         points to the header of the byte array which contains
+    ///         the length.
+    function rawAddress(bytes memory input)
+        internal
+        pure
+        returns (uint256 memoryAddress)
+    {
+        assembly {
+            memoryAddress := input
+        }
+        return memoryAddress;
+    }
+    
+    /// @dev Gets the memory address for the contents of a byte array.
+    /// @param input Byte array to lookup.
+    /// @return memoryAddress Memory address of the contents of the byte array.
+    function contentAddress(bytes memory input)
+        internal
+        pure
+        returns (uint256 memoryAddress)
+    {
+        assembly {
+            memoryAddress := add(input, 32)
+        }
+        return memoryAddress;
+    }
+
+    /// @dev Copies `length` bytes from memory location `source` to `dest`.
+    /// @param dest memory address to copy bytes to.
+    /// @param source memory address to copy bytes from.
+    /// @param length number of bytes to copy.
+    function memCopy(
+        uint256 dest,
+        uint256 source,
+        uint256 length
+    )
+        internal
+        pure
+    {
+        if (length < 32) {
+            // Handle a partial word by reading destination and masking
+            // off the bits we are interested in.
+            // This correctly handles overlap, zero lengths and source == dest
+            assembly {
+                let mask := sub(exp(256, sub(32, length)), 1)
+                let s := and(mload(source), not(mask))
+                let d := and(mload(dest), mask)
+                mstore(dest, or(s, d))
+            }
+        } else {
+            // Skip the O(length) loop when source == dest.
+            if (source == dest) {
+                return;
+            }
+
+            // For large copies we copy whole words at a time. The final
+            // word is aligned to the end of the range (instead of after the
+            // previous) to handle partial words. So a copy will look like this:
+            //
+            //  ####
+            //      ####
+            //          ####
+            //            ####
+            //
+            // We handle overlap in the source and destination range by
+            // changing the copying direction. This prevents us from
+            // overwriting parts of source that we still need to copy.
+            //
+            // This correctly handles source == dest
+            //
+            if (source > dest) {
+                assembly {
+                    // We subtract 32 from `sEnd` and `dEnd` because it
+                    // is easier to compare with in the loop, and these
+                    // are also the addresses we need for copying the
+                    // last bytes.
+                    length := sub(length, 32)
+                    let sEnd := add(source, length)
+                    let dEnd := add(dest, length)
+
+                    // Remember the last 32 bytes of source
+                    // This needs to be done here and not after the loop
+                    // because we may have overwritten the last bytes in
+                    // source already due to overlap.
+                    let last := mload(sEnd)
+
+                    // Copy whole words front to back
+                    // Note: the first check is always true,
+                    // this could have been a do-while loop.
+                    for {} lt(source, sEnd) {} {
+                        mstore(dest, mload(source))
+                        source := add(source, 32)
+                        dest := add(dest, 32)
+                    }
+                    
+                    // Write the last 32 bytes
+                    mstore(dEnd, last)
+                }
+            } else {
+                assembly {
+                    // We subtract 32 from `sEnd` and `dEnd` because those
+                    // are the starting points when copying a word at the end.
+                    length := sub(length, 32)
+                    let sEnd := add(source, length)
+                    let dEnd := add(dest, length)
+
+                    // Remember the first 32 bytes of source
+                    // This needs to be done here and not after the loop
+                    // because we may have overwritten the first bytes in
+                    // source already due to overlap.
+                    let first := mload(source)
+
+                    // Copy whole words back to front
+                    // We use a signed comparisson here to allow dEnd to become
+                    // negative (happens when source and dest < 32). Valid
+                    // addresses in local memory will never be larger than
+                    // 2**255, so they can be safely re-interpreted as signed.
+                    // Note: the first check is always true,
+                    // this could have been a do-while loop.
+                    for {} slt(dest, dEnd) {} {
+                        mstore(dEnd, mload(sEnd))
+                        sEnd := sub(sEnd, 32)
+                        dEnd := sub(dEnd, 32)
+                    }
+                    
+                    // Write the first 32 bytes
+                    mstore(dest, first)
+                }
+            }
+        }
+    }
+    
+    /// @dev Returns a slices from a byte array.
+    /// @param b The byte array to take a slice from.
+    /// @param from The starting index for the slice (inclusive).
+    /// @param to The final index for the slice (exclusive).
+    /// @return result The slice containing bytes at indices [from, to)
+    function slice(bytes memory b, uint256 from, uint256 to)
+        internal
+        pure
+        returns (bytes memory result)
+    {
+        require(
+            from <= to,
+            "FROM_LESS_THAN_TO_REQUIRED"
+        );
+        require(
+            to < b.length,
+            "TO_LESS_THAN_LENGTH_REQUIRED"
+        );
+        
+        // Create a new bytes structure and copy contents
+        result = new bytes(to - from);
+        memCopy(
+            result.contentAddress(),
+            b.contentAddress() + from,
+            result.length);
+        return result;
+    }
+    
+    /// @dev Returns a slice from a byte array without preserving the input.
+    /// @param b The byte array to take a slice from. Will be destroyed in the process.
+    /// @param from The starting index for the slice (inclusive).
+    /// @param to The final index for the slice (exclusive).
+    /// @return result The slice containing bytes at indices [from, to)
+    /// @dev When `from == 0`, the original array will match the slice. In other cases its state will be corrupted.
+    function sliceDestructive(bytes memory b, uint256 from, uint256 to)
+        internal
+        pure
+        returns (bytes memory result)
+    {
+        require(
+            from <= to,
+            "FROM_LESS_THAN_TO_REQUIRED"
+        );
+        require(
+            to < b.length,
+            "TO_LESS_THAN_LENGTH_REQUIRED"
+        );
+        
+        // Create a new bytes structure around [from, to) in-place.
+        assembly {
+            result := add(b, from)
+            mstore(result, sub(to, from))
+        }
+        return result;
+    }
+
+    /// @dev Pops the last byte off of a byte array by modifying its length.
+    /// @param b Byte array that will be modified.
+    /// @return The byte that was popped off.
+    function popLastByte(bytes memory b)
+        internal
+        pure
+        returns (bytes1 result)
+    {
+        require(
+            b.length > 0,
+            "GREATER_THAN_ZERO_LENGTH_REQUIRED"
+        );
+
+        // Store last byte.
+        result = b[b.length - 1];
+
+        assembly {
+            // Decrement length of byte array.
+            let newLen := sub(mload(b), 1)
+            mstore(b, newLen)
+        }
+        return result;
+    }
+
+    /// @dev Pops the last 20 bytes off of a byte array by modifying its length.
+    /// @param b Byte array that will be modified.
+    /// @return The 20 byte address that was popped off.
+    function popLast20Bytes(bytes memory b)
+        internal
+        pure
+        returns (address result)
+    {
+        require(
+            b.length >= 20,
+            "GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED"
+        );
+
+        // Store last 20 bytes.
+        result = readAddress(b, b.length - 20);
+
+        assembly {
+            // Subtract 20 from byte array length.
+            let newLen := sub(mload(b), 20)
+            mstore(b, newLen)
+        }
+        return result;
+    }
+
+    /// @dev Tests equality of two byte arrays.
+    /// @param lhs First byte array to compare.
+    /// @param rhs Second byte array to compare.
+    /// @return True if arrays are the same. False otherwise.
+    function equals(
+        bytes memory lhs,
+        bytes memory rhs
+    )
+        internal
+        pure
+        returns (bool equal)
+    {
+        // Keccak gas cost is 30 + numWords * 6. This is a cheap way to compare.
+        // We early exit on unequal lengths, but keccak would also correctly
+        // handle this.
+        return lhs.length == rhs.length && keccak256(lhs) == keccak256(rhs);
+    }
+
+    /// @dev Reads an address from a position in a byte array.
+    /// @param b Byte array containing an address.
+    /// @param index Index in byte array of address.
+    /// @return address from byte array.
+    function readAddress(
+        bytes memory b,
+        uint256 index
+    )
+        internal
+        pure
+        returns (address result)
+    {
+        require(
+            b.length >= index + 20,  // 20 is length of address
+            "GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED"
+        );
+
+        // Add offset to index:
+        // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
+        // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
+        index += 20;
+
+        // Read address from array memory
+        assembly {
+            // 1. Add index to address of bytes array
+            // 2. Load 32-byte word from memory
+            // 3. Apply 20-byte mask to obtain address
+            result := and(mload(add(b, index)), 0xffffffffffffffffffffffffffffffffffffffff)
+        }
+        return result;
+    }
+
+    /// @dev Writes an address into a specific position in a byte array.
+    /// @param b Byte array to insert address into.
+    /// @param index Index in byte array of address.
+    /// @param input Address to put into byte array.
+    function writeAddress(
+        bytes memory b,
+        uint256 index,
+        address input
+    )
+        internal
+        pure
+    {
+        require(
+            b.length >= index + 20,  // 20 is length of address
+            "GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED"
+        );
+
+        // Add offset to index:
+        // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
+        // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
+        index += 20;
+
+        // Store address into array memory
+        assembly {
+            // The address occupies 20 bytes and mstore stores 32 bytes.
+            // First fetch the 32-byte word where we'll be storing the address, then
+            // apply a mask so we have only the bytes in the word that the address will not occupy.
+            // Then combine these bytes with the address and store the 32 bytes back to memory with mstore.
+
+            // 1. Add index to address of bytes array
+            // 2. Load 32-byte word from memory
+            // 3. Apply 12-byte mask to obtain extra bytes occupying word of memory where we'll store the address
+            let neighbors := and(mload(add(b, index)), 0xffffffffffffffffffffffff0000000000000000000000000000000000000000)
+            
+            // Make sure input address is clean.
+            // (Solidity does not guarantee this)
+            input := and(input, 0xffffffffffffffffffffffffffffffffffffffff)
+
+            // Store the neighbors and address into memory
+            mstore(add(b, index), xor(input, neighbors))
+        }
+    }
+
+    /// @dev Reads a bytes32 value from a position in a byte array.
+    /// @param b Byte array containing a bytes32 value.
+    /// @param index Index in byte array of bytes32 value.
+    /// @return bytes32 value from byte array.
+    function readBytes32(
+        bytes memory b,
+        uint256 index
+    )
+        internal
+        pure
+        returns (bytes32 result)
+    {
+        require(
+            b.length >= index + 32,
+            "GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED"
+        );
+
+        // Arrays are prefixed by a 256 bit length parameter
+        index += 32;
+
+        // Read the bytes32 from array memory
+        assembly {
+            result := mload(add(b, index))
+        }
+        return result;
+    }
+
+    /// @dev Writes a bytes32 into a specific position in a byte array.
+    /// @param b Byte array to insert <input> into.
+    /// @param index Index in byte array of <input>.
+    /// @param input bytes32 to put into byte array.
+    function writeBytes32(
+        bytes memory b,
+        uint256 index,
+        bytes32 input
+    )
+        internal
+        pure
+    {
+        require(
+            b.length >= index + 32,
+            "GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED"
+        );
+
+        // Arrays are prefixed by a 256 bit length parameter
+        index += 32;
+
+        // Read the bytes32 from array memory
+        assembly {
+            mstore(add(b, index), input)
+        }
+    }
+
+    /// @dev Reads a uint256 value from a position in a byte array.
+    /// @param b Byte array containing a uint256 value.
+    /// @param index Index in byte array of uint256 value.
+    /// @return uint256 value from byte array.
+    function readUint256(
+        bytes memory b,
+        uint256 index
+    )
+        internal
+        pure
+        returns (uint256 result)
+    {
+        return uint256(readBytes32(b, index));
+    }
+
+    /// @dev Writes a uint256 into a specific position in a byte array.
+    /// @param b Byte array to insert <input> into.
+    /// @param index Index in byte array of <input>.
+    /// @param input uint256 to put into byte array.
+    function writeUint256(
+        bytes memory b,
+        uint256 index,
+        uint256 input
+    )
+        internal
+        pure
+    {
+        writeBytes32(b, index, bytes32(input));
+    }
+
+    /// @dev Reads an unpadded bytes4 value from a position in a byte array.
+    /// @param b Byte array containing a bytes4 value.
+    /// @param index Index in byte array of bytes4 value.
+    /// @return bytes4 value from byte array.
+    function readBytes4(
+        bytes memory b,
+        uint256 index)
+        internal
+        pure
+        returns (bytes4 result)
+    {
+        require(
+            b.length >= index + 4,
+            "GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED"
+        );
+        assembly {
+            result := mload(add(b, 32))
+            // Solidity does not require us to clean the trailing bytes.
+            // We do it anyway
+            result := and(result, 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000)
+        }
+        return result;
+    }
+
+    /// @dev Reads nested bytes from a specific position.
+    /// @dev NOTE: the returned value overlaps with the input value.
+    ///            Both should be treated as immutable.
+    /// @param b Byte array containing nested bytes.
+    /// @param index Index of nested bytes.
+    /// @return result Nested bytes.
+    function readBytesWithLength(
+        bytes memory b,
+        uint256 index
+    )
+        internal
+        pure
+        returns (bytes memory result)
+    {
+        // Read length of nested bytes
+        uint256 nestedBytesLength = readUint256(b, index);
+        index += 32;
+
+        // Assert length of <b> is valid, given
+        // length of nested bytes
+        require(
+            b.length >= index + nestedBytesLength,
+            "GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED"
+        );
+        
+        // Return a pointer to the byte array as it exists inside `b`
+        assembly {
+            result := add(b, index)
+        }
+        return result;
+    }
+
+    /// @dev Inserts bytes at a specific position in a byte array.
+    /// @param b Byte array to insert <input> into.
+    /// @param index Index in byte array of <input>.
+    /// @param input bytes to insert.
+    function writeBytesWithLength(
+        bytes memory b,
+        uint256 index,
+        bytes memory input
+    )
+        internal
+        pure
+    {
+        // Assert length of <b> is valid, given
+        // length of input
+        require(
+            b.length >= index + 32 /* 32 bytes to store length */ + input.length,
+            "GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED"
+        );
+
+        // Copy <input> into <b>
+        memCopy(
+            b.contentAddress() + index,
+            input.rawAddress(), // includes length of <input>
+            input.length + 32   // +32 bytes to store <input> length
+        );
+    }
+
+    /// @dev Performs a deep copy of a byte array onto another byte array of greater than or equal length.
+    /// @param dest Byte array that will be overwritten with source bytes.
+    /// @param source Byte array to copy onto dest bytes.
+    function deepCopyBytes(
+        bytes memory dest,
+        bytes memory source
+    )
+        internal
+        pure
+    {
+        uint256 sourceLen = source.length;
+        // Dest length must be >= source length, or some bytes would not be copied.
+        require(
+            dest.length >= sourceLen,
+            "GREATER_OR_EQUAL_TO_SOURCE_BYTES_LENGTH_REQUIRED"
+        );
+        memCopy(
+            dest.contentAddress(),
+            source.contentAddress(),
+            sourceLen
+        );
+    }
+}
diff --git a/packages/contracts/src/2.0.0/utils/Ownable/IOwnable.sol b/packages/contracts/src/2.0.0/utils/Ownable/IOwnable.sol
new file mode 100644
index 000000000..e77680903
--- /dev/null
+++ b/packages/contracts/src/2.0.0/utils/Ownable/IOwnable.sol
@@ -0,0 +1,14 @@
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+/*
+ * Ownable
+ *
+ * Base contract with an owner.
+ * Provides onlyOwner modifier, which prevents function from running if it is called by anyone other than the owner.
+ */
+
+contract IOwnable {
+    function transferOwnership(address newOwner)
+        public;
+}
diff --git a/packages/contracts/src/2.0.0/utils/Ownable/Ownable.sol b/packages/contracts/src/2.0.0/utils/Ownable/Ownable.sol
new file mode 100644
index 000000000..6f5761cc7
--- /dev/null
+++ b/packages/contracts/src/2.0.0/utils/Ownable/Ownable.sol
@@ -0,0 +1,38 @@
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+/*
+ * Ownable
+ *
+ * Base contract with an owner.
+ * Provides onlyOwner modifier, which prevents function from running if it is called by anyone other than the owner.
+ */
+
+import "./IOwnable.sol";
+
+contract Ownable is IOwnable {
+    address public owner;
+
+    constructor ()
+        public
+    {
+        owner = msg.sender;
+    }
+
+    modifier onlyOwner() {
+        require(
+            msg.sender == owner,
+            "ONLY_CONTRACT_OWNER"
+        );
+        _;
+    }
+
+    function transferOwnership(address newOwner)
+        public
+        onlyOwner
+    {
+        if (newOwner != address(0)) {
+            owner = newOwner;
+        }
+    }
+}
diff --git a/packages/contracts/src/2.0.0/utils/SafeMath/SafeMath.sol b/packages/contracts/src/2.0.0/utils/SafeMath/SafeMath.sol
new file mode 100644
index 000000000..e137f6ca5
--- /dev/null
+++ b/packages/contracts/src/2.0.0/utils/SafeMath/SafeMath.sol
@@ -0,0 +1,74 @@
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+contract SafeMath {
+    function safeMul(uint a, uint b)
+        internal
+        pure
+        returns (uint256)
+    {
+        uint c = a * b;
+        assert(a == 0 || c / a == b);
+        return c;
+    }
+
+    function safeDiv(uint a, uint b)
+        internal
+        pure
+        returns (uint256)
+    {
+        uint c = a / b;
+        return c;
+    }
+
+    function safeSub(uint a, uint b)
+        internal
+        pure
+        returns (uint256)
+    {
+        assert(b <= a);
+        return a - b;
+    }
+
+    function safeAdd(uint a, uint b)
+        internal
+        pure
+        returns (uint256)
+    {
+        uint c = a + b;
+        assert(c >= a);
+        return c;
+    }
+
+    function max64(uint64 a, uint64 b)
+        internal
+        pure
+        returns (uint256)
+    {
+        return a >= b ? a : b;
+    }
+
+    function min64(uint64 a, uint64 b)
+        internal
+        pure
+        returns (uint256)
+    {
+        return a < b ? a : b;
+    }
+
+    function max256(uint256 a, uint256 b)
+        internal
+        pure
+        returns (uint256)
+    {
+        return a >= b ? a : b;
+    }
+
+    function min256(uint256 a, uint256 b)
+        internal
+        pure
+        returns (uint256)
+    {
+        return a < b ? a : b;
+    }
+}