40 files changed, 300 insertions, 304 deletions
diff --git a/contracts/core/README.md b/contracts/core/README.md
index 922ea21ad..d055705c2 100644
--- a/contracts/core/README.md
+++ b/contracts/core/README.md
@@ -8,8 +8,6 @@ Contracts that make up and interact with version 2.0.0 of the protocol can be fo
 
 *   [protocol](./contracts/protocol)
     *   This directory contains the contracts that make up version 2.0.0. A full specification can be found [here](https://github.com/0xProject/0x-protocol-specification/blob/master/v2/v2-specification.md).
-*   [extensions](./contracts/extensions)
-    *   This directory contains contracts that interact with the 2.0.0 contracts and will be used in production, such as the [Forwarder](https://github.com/0xProject/0x-protocol-specification/blob/master/v2/forwarder-specification.md) contract.
 *   [test](./contracts/test)
     *   This directory contains mocks and other contracts that are used solely for testing contracts within the other directories.
 
diff --git a/contracts/core/compiler.json b/contracts/core/compiler.json
index 3f869024c..10e5bb0a1 100644
--- a/contracts/core/compiler.json
+++ b/contracts/core/compiler.json
@@ -20,14 +20,11 @@
     },
     "contracts": [
         "AssetProxyOwner",
-        "DutchAuction",
         "ERC20Proxy",
         "ERC721Proxy",
         "Exchange",
-        "Forwarder",
         "MixinAuthorizable",
         "MultiAssetProxy",
-        "OrderValidator",
         "TestAssetProxyOwner",
         "TestAssetProxyDispatcher",
         "TestExchangeInternals",
diff --git a/contracts/core/package.json b/contracts/core/package.json
index 62547c311..b7077f4b4 100644
--- a/contracts/core/package.json
+++ b/contracts/core/package.json
@@ -33,7 +33,7 @@
         "lint-contracts": "solhint contracts/**/**/**/**/*.sol"
     },
     "config": {
-        "abis": "generated-artifacts/@(AssetProxyOwner|DutchAuction|ERC20Proxy|ERC721Proxy|Forwarder|Exchange|MixinAuthorizable|MultiAssetProxy|OrderValidator|TestAssetProxyOwner|TestAssetProxyDispatcher|TestExchangeInternals|TestStaticCallReceiver).json"
+        "abis": "generated-artifacts/@(AssetProxyOwner|ERC20Proxy|ERC721Proxy|Exchange|MixinAuthorizable|MultiAssetProxy|TestSignatureValidator|TestAssetProxyOwner|TestAssetProxyDispatcher|TestExchangeInternals|TestStaticCallReceiver).json"
     },
     "repository": {
         "type": "git",
diff --git a/contracts/core/src/artifacts/index.ts b/contracts/core/src/artifacts/index.ts
index 7b598a6d9..c5d12f10b 100644
--- a/contracts/core/src/artifacts/index.ts
+++ b/contracts/core/src/artifacts/index.ts
@@ -1,14 +1,11 @@
 import { ContractArtifact } from 'ethereum-types';
 
 import * as AssetProxyOwner from '../../generated-artifacts/AssetProxyOwner.json';
-import * as DutchAuction from '../../generated-artifacts/DutchAuction.json';
 import * as ERC20Proxy from '../../generated-artifacts/ERC20Proxy.json';
 import * as ERC721Proxy from '../../generated-artifacts/ERC721Proxy.json';
 import * as Exchange from '../../generated-artifacts/Exchange.json';
-import * as Forwarder from '../../generated-artifacts/Forwarder.json';
 import * as MixinAuthorizable from '../../generated-artifacts/MixinAuthorizable.json';
 import * as MultiAssetProxy from '../../generated-artifacts/MultiAssetProxy.json';
-import * as OrderValidator from '../../generated-artifacts/OrderValidator.json';
 import * as TestAssetProxyDispatcher from '../../generated-artifacts/TestAssetProxyDispatcher.json';
 import * as TestAssetProxyOwner from '../../generated-artifacts/TestAssetProxyOwner.json';
 import * as TestExchangeInternals from '../../generated-artifacts/TestExchangeInternals.json';
@@ -17,14 +14,11 @@ import * as TestStaticCallReceiver from '../../generated-artifacts/TestStaticCal
 
 export const artifacts = {
     AssetProxyOwner: AssetProxyOwner as ContractArtifact,
-    DutchAuction: DutchAuction as ContractArtifact,
     ERC20Proxy: ERC20Proxy as ContractArtifact,
     ERC721Proxy: ERC721Proxy as ContractArtifact,
     Exchange: Exchange as ContractArtifact,
-    Forwarder: Forwarder as ContractArtifact,
     MixinAuthorizable: MixinAuthorizable as ContractArtifact,
     MultiAssetProxy: MultiAssetProxy as ContractArtifact,
-    OrderValidator: OrderValidator as ContractArtifact,
     TestAssetProxyDispatcher: TestAssetProxyDispatcher as ContractArtifact,
     TestAssetProxyOwner: TestAssetProxyOwner as ContractArtifact,
     TestExchangeInternals: TestExchangeInternals as ContractArtifact,
diff --git a/contracts/core/src/index.ts b/contracts/core/src/index.ts
index d55f08ea2..ba813e7ca 100644
--- a/contracts/core/src/index.ts
+++ b/contracts/core/src/index.ts
@@ -1,2 +1,3 @@
 export * from './artifacts';
 export * from './wrappers';
+export * from '../test/utils';
diff --git a/contracts/core/src/wrappers/index.ts b/contracts/core/src/wrappers/index.ts
index ce3714ed7..01b121054 100644
--- a/contracts/core/src/wrappers/index.ts
+++ b/contracts/core/src/wrappers/index.ts
@@ -1,11 +1,8 @@
 export * from '../../generated-wrappers/asset_proxy_owner';
-export * from '../../generated-wrappers/dutch_auction';
 export * from '../../generated-wrappers/erc20_proxy';
 export * from '../../generated-wrappers/erc721_proxy';
 export * from '../../generated-wrappers/exchange';
-export * from '../../generated-wrappers/forwarder';
 export * from '../../generated-wrappers/mixin_authorizable';
-export * from '../../generated-wrappers/order_validator';
 export * from '../../generated-wrappers/test_asset_proxy_dispatcher';
 export * from '../../generated-wrappers/test_asset_proxy_owner';
 export * from '../../generated-wrappers/test_exchange_internals';
diff --git a/contracts/core/test/exchange/signature_validator.ts b/contracts/core/test/exchange/signature_validator.ts
index a968570b6..9d154d30a 100644
--- a/contracts/core/test/exchange/signature_validator.ts
+++ b/contracts/core/test/exchange/signature_validator.ts
@@ -1,3 +1,5 @@
+import { ValidatorContract, WalletContract } from '@0x/contracts-examples';
+import { artifacts as examplesArtifacts } from '@0x/contracts-examples';
 import {
     addressUtils,
     chaiSetup,
@@ -22,8 +24,6 @@ import {
     TestSignatureValidatorContract,
     TestSignatureValidatorSignatureValidatorApprovalEventArgs,
     TestStaticCallReceiverContract,
-    ValidatorContract,
-    WalletContract,
 } from '../../src';
 
 chaiSetup.configure();
@@ -62,13 +62,13 @@ describe('MixinSignatureValidator', () => {
             txDefaults,
         );
         testWallet = await WalletContract.deployFrom0xArtifactAsync(
-            artifacts.Wallet,
+            examplesArtifacts.Wallet,
             provider,
             txDefaults,
             signerAddress,
         );
         testValidator = await ValidatorContract.deployFrom0xArtifactAsync(
-            artifacts.Validator,
+            examplesArtifacts.Validator,
             provider,
             txDefaults,
             signerAddress,
diff --git a/contracts/core/test/exchange/transactions.ts b/contracts/core/test/exchange/transactions.ts
index ad0ca41c2..746f3cb04 100644
--- a/contracts/core/test/exchange/transactions.ts
+++ b/contracts/core/test/exchange/transactions.ts
@@ -1,3 +1,4 @@
+import { artifacts as examplesArtifacts, ExchangeWrapperContract, WhitelistContract } from '@0x/contracts-examples';
 import {
     chaiSetup,
     constants,
@@ -21,8 +22,6 @@ import * as _ from 'lodash';
 
 import { ERC20ProxyContract } from '../../generated-wrappers/erc20_proxy';
 import { ExchangeContract } from '../../generated-wrappers/exchange';
-import { ExchangeWrapperContract } from '../../generated-wrappers/exchange_wrapper';
-import { WhitelistContract } from '../../generated-wrappers/whitelist';
 import { artifacts } from '../../src/artifacts';
 import { ERC20Wrapper } from '../utils/erc20_wrapper';
 import { ExchangeWrapper } from '../utils/exchange_wrapper';
@@ -222,7 +221,7 @@ describe('Exchange transactions', () => {
 
             before(async () => {
                 exchangeWrapperContract = await ExchangeWrapperContract.deployFrom0xArtifactAsync(
-                    artifacts.ExchangeWrapper,
+                    examplesArtifacts.ExchangeWrapper,
                     provider,
                     txDefaults,
                     exchange.address,
@@ -336,7 +335,7 @@ describe('Exchange transactions', () => {
 
         before(async () => {
             whitelist = await WhitelistContract.deployFrom0xArtifactAsync(
-                artifacts.Whitelist,
+                examplesArtifacts.Whitelist,
                 provider,
                 txDefaults,
                 exchange.address,
diff --git a/contracts/core/test/tutorials/arbitrage.ts b/contracts/core/test/tutorials/arbitrage.ts
deleted file mode 100644
index 78e0bc238..000000000
--- a/contracts/core/test/tutorials/arbitrage.ts
+++ /dev/null
@@ -1,260 +0,0 @@
-// import { ECSignature, SignedOrder, ZeroEx } from '0x.js';
-// import { BlockchainLifecycle, devConstants, web3Factory } from '@0x/dev-utils';
-// import { ExchangeContractErrs } from 'ethereum-types';
-// import { BigNumber } from '@0x/utils';
-// import { Web3Wrapper } from '@0x/web3-wrapper';
-// import * as chai from 'chai';
-// import ethUtil = require('ethereumjs-util');
-// import * as Web3 from 'web3';
-
-// import { AccountLevelsContract } from '../../src/generated_contract_wrappers/account_levels';
-// import { ArbitrageContract } from '../../src/generated_contract_wrappers/arbitrage';
-// import { DummyTokenContract } from '../../src/generated_contract_wrappers/dummy_token';
-// import { EtherDeltaContract } from '../../src/generated_contract_wrappers/ether_delta';
-// import { ExchangeContract } from '../../src/generated_contract_wrappers/exchange';
-// import { TokenTransferProxyContract } from '../../src/generated_contract_wrappers/token_transfer_proxy';
-// import { artifacts } from '../../util/artifacts';
-// import { Balances } from '../../util/balances';
-// import { constants } from '../../util/constants';
-// import { crypto } from '../../util/crypto';
-// import { ExchangeWrapper } from '../../util/exchange_wrapper';
-// import { OrderFactory } from '../../util/order_factory';
-// import { BalancesByOwner, ContractName } from '../../util/types';
-// import { chaiSetup } from '../utils/chai_setup';
-
-// import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
-
-// chaiSetup.configure();
-// const expect = chai.expect;
-// const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
-
-// describe('Arbitrage', () => {
-//     let coinbase: string;
-//     let maker: string;
-//     let edMaker: string;
-//     let edFrontRunner: string;
-//     let amountGet: BigNumber;
-//     let amountGive: BigNumber;
-//     let makerTokenAmount: BigNumber;
-//     let takerTokenAmount: BigNumber;
-//     const feeRecipient = constants.NULL_ADDRESS;
-//     const INITIAL_BALANCE = ZeroEx.toBaseUnitAmount(new BigNumber(10000), 18);
-//     const INITIAL_ALLOWANCE = ZeroEx.toBaseUnitAmount(new BigNumber(10000), 18);
-
-//     let weth: DummyTokenContract;
-//     let zrx: DummyTokenContract;
-//     let arbitrage: ArbitrageContract;
-//     let etherDelta: EtherDeltaContract;
-
-//     let signedOrder: SignedOrder;
-//     let exWrapper: ExchangeWrapper;
-//     let orderFactory: OrderFactory;
-
-//     let zeroEx: ZeroEx;
-
-//     // From a bird's eye view - we create two orders.
-//     // 0x order of 1 ZRX (maker) for 1 WETH (taker)
-//     // ED order of 2 WETH (tokenGive) for 1 ZRX (tokenGet)
-//     // And then we do an atomic arbitrage between them which gives us 1 WETH.
-//     before(async () => {
-//         const accounts = await web3Wrapper.getAvailableAddressesAsync();
-//         [coinbase, maker, edMaker, edFrontRunner] = accounts;
-//         weth = await DummyTokenContract.deployFrom0xArtifactAsync(
-//             artifacts.DummyToken,
-//             provider,
-//             txDefaults,
-//             constants.DUMMY_TOKEN_NAME,
-//             constants.DUMMY_TOKEN_SYMBOL,
-//             constants.DUMMY_TOKEN_DECIMALS,
-//             constants.DUMMY_TOKEN_TOTAL_SUPPLY,
-//         );
-//         zrx = await DummyTokenContract.deployFrom0xArtifactAsync(
-//             artifacts.DummyToken,
-//             provider,
-//             txDefaults,
-//             constants.DUMMY_TOKEN_NAME,
-//             constants.DUMMY_TOKEN_SYMBOL,
-//             constants.DUMMY_TOKEN_DECIMALS,
-//             constants.DUMMY_TOKEN_TOTAL_SUPPLY,
-//         );
-//         const accountLevels = await AccountLevelsContract.deployFrom0xArtifactAsync(
-//             artifacts.AccountLevels,
-//             provider,
-//             txDefaults,
-//         );
-//         const edAdminAddress = accounts[0];
-//         const edMakerFee = new BigNumber(0);
-//         const edTakerFee = new BigNumber(0);
-//         const edFeeRebate = new BigNumber(0);
-//         etherDelta = await EtherDeltaContract.deployFrom0xArtifactAsync(
-//             artifacts.EtherDelta,
-//             provider,
-//             txDefaults,
-//             edAdminAddress,
-//             feeRecipient,
-//             accountLevels.address,
-//             edMakerFee,
-//             edTakerFee,
-//             edFeeRebate,
-//         );
-//         const tokenTransferProxy = await TokenTransferProxyContract.deployFrom0xArtifactAsync(
-//             artifacts.TokenTransferProxy,
-//             provider,
-//             txDefaults,
-//         );
-//         const exchange = await ExchangeContract.deployFrom0xArtifactAsync(
-//             artifacts.Exchange,
-//             provider,
-//             txDefaults,
-//             zrx.address,
-//             tokenTransferProxy.address,
-//         );
-//         await tokenTransferProxy.addAuthorizedAddress.sendTransactionAsync(exchange.address, { from: accounts[0] });
-//         zeroEx = new ZeroEx(provider, {
-//             exchangeContractAddress: exchange.address,
-//             networkId: constants.TESTRPC_NETWORK_ID,
-//         });
-//         exWrapper = new ExchangeWrapper(exchange, provider);
-
-//         makerTokenAmount = ZeroEx.toBaseUnitAmount(new BigNumber(1), 18);
-//         takerTokenAmount = makerTokenAmount;
-//         const defaultOrderParams = {
-//             exchangeContractAddress: exchange.address,
-//             maker,
-//             feeRecipient,
-//             makerTokenAddress: zrx.address,
-//             takerTokenAddress: weth.address,
-//             makerTokenAmount,
-//             takerTokenAmount,
-//             makerFee: new BigNumber(0),
-//             takerFee: new BigNumber(0),
-//         };
-//         orderFactory = new OrderFactory(zeroEx, defaultOrderParams);
-//         arbitrage = await ArbitrageContract.deployFrom0xArtifactAsync(
-//             artifacts.Arbitrage,
-//             provider,
-//             txDefaults,
-//             exchange.address,
-//             etherDelta.address,
-//             tokenTransferProxy.address,
-//         );
-//         // Enable arbitrage and withdrawals of tokens
-//         await arbitrage.setAllowances.sendTransactionAsync(weth.address, { from: coinbase });
-//         await arbitrage.setAllowances.sendTransactionAsync(zrx.address, { from: coinbase });
-
-//         // Give some tokens to arbitrage contract
-//         await weth.setBalance.sendTransactionAsync(arbitrage.address, takerTokenAmount, { from: coinbase });
-
-//         // Fund the maker on exchange side
-//         await zrx.setBalance.sendTransactionAsync(maker, makerTokenAmount, { from: coinbase });
-//         // Set the allowance for the maker on Exchange side
-//         await zrx.approve.sendTransactionAsync(tokenTransferProxy.address, INITIAL_ALLOWANCE, { from: maker });
-
-//         amountGive = ZeroEx.toBaseUnitAmount(new BigNumber(2), 18);
-//         // Fund the maker on EtherDelta side
-//         await weth.setBalance.sendTransactionAsync(edMaker, amountGive, { from: coinbase });
-//         // Set the allowance for the maker on EtherDelta side
-//         await weth.approve.sendTransactionAsync(etherDelta.address, INITIAL_ALLOWANCE, { from: edMaker });
-//         // Deposit maker funds into EtherDelta
-//         await etherDelta.depositToken.sendTransactionAsync(weth.address, amountGive, { from: edMaker });
-
-//         amountGet = makerTokenAmount;
-//         // Fund the front runner on EtherDelta side
-//         await zrx.setBalance.sendTransactionAsync(edFrontRunner, amountGet, { from: coinbase });
-//         // Set the allowance for the front-runner on EtherDelta side
-//         await zrx.approve.sendTransactionAsync(etherDelta.address, INITIAL_ALLOWANCE, { from: edFrontRunner });
-//         // Deposit front runner funds into EtherDelta
-//         await etherDelta.depositToken.sendTransactionAsync(zrx.address, amountGet, { from: edFrontRunner });
-//     });
-//     beforeEach(async () => {
-//         await blockchainLifecycle.startAsync();
-//     });
-//     afterEach(async () => {
-//         await blockchainLifecycle.revertAsync();
-//     });
-//     describe('makeAtomicTrade', () => {
-//         let addresses: string[];
-//         let values: BigNumber[];
-//         let v: number[];
-//         let r: string[];
-//         let s: string[];
-//         let tokenGet: string;
-//         let tokenGive: string;
-//         let expires: BigNumber;
-//         let nonce: BigNumber;
-//         let edSignature: ECSignature;
-//         before(async () => {
-//             signedOrder = await orderFactory.newSignedOrderAsync();
-//             tokenGet = zrx.address;
-//             tokenGive = weth.address;
-//             const blockNumber = await web3Wrapper.getBlockNumberAsync();
-//             const ED_ORDER_EXPIRATION_IN_BLOCKS = 10;
-//             expires = new BigNumber(blockNumber + ED_ORDER_EXPIRATION_IN_BLOCKS);
-//             nonce = new BigNumber(42);
-//             const edOrderHash = `0x${crypto
-//                 .solSHA256([etherDelta.address, tokenGet, amountGet, tokenGive, amountGive, expires, nonce])
-//                 .toString('hex')}`;
-//             const shouldAddPersonalMessagePrefix = false;
-//             edSignature = await zeroEx.signOrderHashAsync(edOrderHash, edMaker, shouldAddPersonalMessagePrefix);
-//             addresses = [
-//                 signedOrder.maker,
-//                 signedOrder.taker,
-//                 signedOrder.makerTokenAddress,
-//                 signedOrder.takerTokenAddress,
-//                 signedOrder.feeRecipient,
-//                 edMaker,
-//             ];
-//             const fillTakerTokenAmount = takerTokenAmount;
-//             const edFillAmount = makerTokenAmount;
-//             values = [
-//                 signedOrder.makerTokenAmount,
-//                 signedOrder.takerTokenAmount,
-//                 signedOrder.makerFee,
-//                 signedOrder.takerFee,
-//                 signedOrder.expirationUnixTimestampSec,
-//                 signedOrder.salt,
-//                 fillTakerTokenAmount,
-//                 amountGet,
-//                 amountGive,
-//                 expires,
-//                 nonce,
-//                 edFillAmount,
-//             ];
-//             v = [signedOrder.ecSignature.v, edSignature.v];
-//             r = [signedOrder.ecSignature.r, edSignature.r];
-//             s = [signedOrder.ecSignature.s, edSignature.s];
-//         });
-//         it('should successfully execute the arbitrage if not front-runned', async () => {
-//             const txHash = await arbitrage.makeAtomicTrade.sendTransactionAsync(addresses, values, v, r, s, {
-//                 from: coinbase,
-//             });
-//             const res = await zeroEx.awaitTransactionMinedAsync(txHash);
-//             const postBalance = await weth.balanceOf.callAsync(arbitrage.address);
-//             expect(postBalance).to.be.bignumber.equal(amountGive);
-//         });
-//         it('should fail and revert if front-runned', async () => {
-//             const preBalance = await weth.balanceOf.callAsync(arbitrage.address);
-//             // Front-running transaction
-//             await etherDelta.trade.sendTransactionAsync(
-//                 tokenGet,
-//                 amountGet,
-//                 tokenGive,
-//                 amountGive,
-//                 expires,
-//                 nonce,
-//                 edMaker,
-//                 edSignature.v,
-//                 edSignature.r,
-//                 edSignature.s,
-//                 amountGet,
-//                 { from: edFrontRunner },
-//             );
-//             // tslint:disable-next-line:await-promise
-//             await expect(
-//                 arbitrage.makeAtomicTrade.sendTransactionAsync(addresses, values, v, r, s, { from: coinbase }),
-//             ).to.be.rejectedWith(constants.REVERT);
-//             const postBalance = await weth.balanceOf.callAsync(arbitrage.address);
-//             expect(preBalance).to.be.bignumber.equal(postBalance);
-//         });
-//     });
-// });
diff --git a/contracts/core/test/utils/index.ts b/contracts/core/test/utils/index.ts
new file mode 100644
index 000000000..75cd88666
--- /dev/null
+++ b/contracts/core/test/utils/index.ts
@@ -0,0 +1,3 @@
+export * from './exchange_wrapper';
+export * from './erc20_wrapper';
+export * from './erc721_wrapper';
diff --git a/contracts/core/tsconfig.json b/contracts/core/tsconfig.json
index d6adef2c5..db872fc32 100644
--- a/contracts/core/tsconfig.json
+++ b/contracts/core/tsconfig.json
@@ -8,14 +8,11 @@
     "include": ["./src/**/*", "./test/**/*", "./generated-wrappers/**/*"],
     "files": [
         "./generated-artifacts/AssetProxyOwner.json",
-        "./generated-artifacts/DutchAuction.json",
         "./generated-artifacts/ERC20Proxy.json",
         "./generated-artifacts/ERC721Proxy.json",
         "./generated-artifacts/Exchange.json",
-        "./generated-artifacts/Forwarder.json",
         "./generated-artifacts/MixinAuthorizable.json",
         "./generated-artifacts/MultiAssetProxy.json",
-        "./generated-artifacts/OrderValidator.json",
         "./generated-artifacts/TestAssetProxyDispatcher.json",
         "./generated-artifacts/TestAssetProxyOwner.json",
         "./generated-artifacts/TestExchangeInternals.json",
diff --git a/contracts/extensions/.solhint.json b/contracts/extensions/.solhint.json
new file mode 100644
index 000000000..076afe9f3
--- /dev/null
+++ b/contracts/extensions/.solhint.json
@@ -0,0 +1,20 @@
+{
+    "extends": "default",
+    "rules": {
+        "avoid-low-level-calls": false,
+        "avoid-tx-origin": "warn",
+        "bracket-align": false,
+        "code-complexity": false,
+        "const-name-snakecase": "error",
+        "expression-indent": "error",
+        "function-max-lines": false,
+        "func-order": "error",
+        "indent": ["error", 4],
+        "max-line-length": ["warn", 160],
+        "no-inline-assembly": false,
+        "quotes": ["error", "double"],
+        "separate-by-one-line-in-contract": "error",
+        "space-after-comma": "error",
+        "statement-indent": "error"
+    }
+}
diff --git a/contracts/extensions/README.md b/contracts/extensions/README.md
new file mode 100644
index 000000000..820f6e78a
--- /dev/null
+++ b/contracts/extensions/README.md
@@ -0,0 +1,69 @@
+## Contract extensions
+
+Smart contracts that implement extensions for the 0x protocol.
+
+## Usage
+
+Contract extensions of the protocol can be found in the [contracts](./contracts) directory. This directory contains contracts that interact with the 2.0.0 contracts and will be used in production, such as the [Forwarder](https://github.com/0xProject/0x-protocol-specification/blob/master/v2/forwarder-specification.md) contract.
+
+## Bug bounty
+
+A bug bounty for the 2.0.0 contracts is ongoing! Instructions can be found [here](https://0xproject.com/wiki#Bug-Bounty).
+
+## Contributing
+
+We strongly recommend that the community help us make improvements and determine the future direction of the protocol. To report bugs within this package, please create an issue in this repository.
+
+For proposals regarding the 0x protocol's smart contract architecture, message format, or additional functionality, go to the [0x Improvement Proposals (ZEIPs)](https://github.com/0xProject/ZEIPs) repository and follow the contribution guidelines provided therein.
+
+Please read our [contribution guidelines](../../CONTRIBUTING.md) before getting started.
+
+### Install Dependencies
+
+If you don't have yarn workspaces enabled (Yarn < v1.0) - enable them:
+
+```bash
+yarn config set workspaces-experimental true
+```
+
+Then install dependencies
+
+```bash
+yarn install
+```
+
+### Build
+
+To build this package and all other monorepo packages that it depends on, run the following from the monorepo root directory:
+
+```bash
+PKG=@0x/contracts-extensions yarn build
+```
+
+Or continuously rebuild on change:
+
+```bash
+PKG=@0x/contracts-extensions yarn watch
+```
+
+### Clean
+
+```bash
+yarn clean
+```
+
+### Lint
+
+```bash
+yarn lint
+```
+
+### Run Tests
+
+```bash
+yarn test
+```
+
+#### Testing options
+
+Contracts testing options like coverage, profiling, revert traces or backing node choosing - are described [here](../TESTING.md).
diff --git a/contracts/extensions/compiler.json b/contracts/extensions/compiler.json
new file mode 100644
index 000000000..807429976
--- /dev/null
+++ b/contracts/extensions/compiler.json
@@ -0,0 +1,22 @@
+{
+    "artifactsDir": "./generated-artifacts",
+    "contractsDir": "./contracts",
+    "compilerSettings": {
+        "optimizer": {
+            "enabled": true,
+            "runs": 1000000
+        },
+        "outputSelection": {
+            "*": {
+                "*": [
+                    "abi",
+                    "evm.bytecode.object",
+                    "evm.bytecode.sourceMap",
+                    "evm.deployedBytecode.object",
+                    "evm.deployedBytecode.sourceMap"
+                ]
+            }
+        }
+    },
+    "contracts": ["DutchAuction", "Forwarder", "OrderValidator"]
+}
diff --git a/contracts/core/contracts/extensions/DutchAuction/DutchAuction.sol b/contracts/extensions/contracts/DutchAuction/DutchAuction.sol
index 9c9f3990a..9c9f3990a 100644
--- a/contracts/core/contracts/extensions/DutchAuction/DutchAuction.sol
+++ b/contracts/extensions/contracts/DutchAuction/DutchAuction.sol
diff --git a/contracts/core/contracts/extensions/Forwarder/Forwarder.sol b/contracts/extensions/contracts/Forwarder/Forwarder.sol
index 94dec40ed..94dec40ed 100644
--- a/contracts/core/contracts/extensions/Forwarder/Forwarder.sol
+++ b/contracts/extensions/contracts/Forwarder/Forwarder.sol
diff --git a/contracts/core/contracts/extensions/Forwarder/MixinAssets.sol b/contracts/extensions/contracts/Forwarder/MixinAssets.sol
index 3ebf75161..3ebf75161 100644
--- a/contracts/core/contracts/extensions/Forwarder/MixinAssets.sol
+++ b/contracts/extensions/contracts/Forwarder/MixinAssets.sol
diff --git a/contracts/core/contracts/extensions/Forwarder/MixinExchangeWrapper.sol b/contracts/extensions/contracts/Forwarder/MixinExchangeWrapper.sol
index 210eb14c2..210eb14c2 100644
--- a/contracts/core/contracts/extensions/Forwarder/MixinExchangeWrapper.sol
+++ b/contracts/extensions/contracts/Forwarder/MixinExchangeWrapper.sol
diff --git a/contracts/core/contracts/extensions/Forwarder/MixinForwarderCore.sol b/contracts/extensions/contracts/Forwarder/MixinForwarderCore.sol
index bab78d79b..bab78d79b 100644
--- a/contracts/core/contracts/extensions/Forwarder/MixinForwarderCore.sol
+++ b/contracts/extensions/contracts/Forwarder/MixinForwarderCore.sol
diff --git a/contracts/core/contracts/extensions/Forwarder/MixinWeth.sol b/contracts/extensions/contracts/Forwarder/MixinWeth.sol
index 2a281f3ae..2a281f3ae 100644
--- a/contracts/core/contracts/extensions/Forwarder/MixinWeth.sol
+++ b/contracts/extensions/contracts/Forwarder/MixinWeth.sol
diff --git a/contracts/core/contracts/extensions/Forwarder/interfaces/IAssets.sol b/contracts/extensions/contracts/Forwarder/interfaces/IAssets.sol
index 1e034c003..1e034c003 100644
--- a/contracts/core/contracts/extensions/Forwarder/interfaces/IAssets.sol
+++ b/contracts/extensions/contracts/Forwarder/interfaces/IAssets.sol
diff --git a/contracts/core/contracts/extensions/Forwarder/interfaces/IForwarder.sol b/contracts/extensions/contracts/Forwarder/interfaces/IForwarder.sol
index f5a26e2ba..f5a26e2ba 100644
--- a/contracts/core/contracts/extensions/Forwarder/interfaces/IForwarder.sol
+++ b/contracts/extensions/contracts/Forwarder/interfaces/IForwarder.sol
diff --git a/contracts/core/contracts/extensions/Forwarder/interfaces/IForwarderCore.sol b/contracts/extensions/contracts/Forwarder/interfaces/IForwarderCore.sol
index eede20bb8..eede20bb8 100644
--- a/contracts/core/contracts/extensions/Forwarder/interfaces/IForwarderCore.sol
+++ b/contracts/extensions/contracts/Forwarder/interfaces/IForwarderCore.sol
diff --git a/contracts/core/contracts/extensions/Forwarder/libs/LibConstants.sol b/contracts/extensions/contracts/Forwarder/libs/LibConstants.sol
index 4a81abf76..4a81abf76 100644
--- a/contracts/core/contracts/extensions/Forwarder/libs/LibConstants.sol
+++ b/contracts/extensions/contracts/Forwarder/libs/LibConstants.sol
diff --git a/contracts/core/contracts/extensions/Forwarder/libs/LibForwarderErrors.sol b/contracts/extensions/contracts/Forwarder/libs/LibForwarderErrors.sol
index fb3ade1db..fb3ade1db 100644
--- a/contracts/core/contracts/extensions/Forwarder/libs/LibForwarderErrors.sol
+++ b/contracts/extensions/contracts/Forwarder/libs/LibForwarderErrors.sol
diff --git a/contracts/core/contracts/extensions/Forwarder/mixins/MAssets.sol b/contracts/extensions/contracts/Forwarder/mixins/MAssets.sol
index 9e7f80d97..9e7f80d97 100644
--- a/contracts/core/contracts/extensions/Forwarder/mixins/MAssets.sol
+++ b/contracts/extensions/contracts/Forwarder/mixins/MAssets.sol
diff --git a/contracts/core/contracts/extensions/Forwarder/mixins/MExchangeWrapper.sol b/contracts/extensions/contracts/Forwarder/mixins/MExchangeWrapper.sol
index d9e71786a..d9e71786a 100644
--- a/contracts/core/contracts/extensions/Forwarder/mixins/MExchangeWrapper.sol
+++ b/contracts/extensions/contracts/Forwarder/mixins/MExchangeWrapper.sol
diff --git a/contracts/core/contracts/extensions/Forwarder/mixins/MWeth.sol b/contracts/extensions/contracts/Forwarder/mixins/MWeth.sol
index 88e77be4e..88e77be4e 100644
--- a/contracts/core/contracts/extensions/Forwarder/mixins/MWeth.sol
+++ b/contracts/extensions/contracts/Forwarder/mixins/MWeth.sol
diff --git a/contracts/core/contracts/extensions/OrderValidator/OrderValidator.sol b/contracts/extensions/contracts/OrderValidator/OrderValidator.sol
index 33dd1326c..33dd1326c 100644
--- a/contracts/core/contracts/extensions/OrderValidator/OrderValidator.sol
+++ b/contracts/extensions/contracts/OrderValidator/OrderValidator.sol
diff --git a/contracts/extensions/package.json b/contracts/extensions/package.json
new file mode 100644
index 000000000..95db0c5ac
--- /dev/null
+++ b/contracts/extensions/package.json
@@ -0,0 +1,95 @@
+{
+    "private": true,
+    "name": "@0x/contracts-extensions",
+    "version": "1.0.0",
+    "engines": {
+        "node": ">=6.12"
+    },
+    "description": "Smart contract extensions of 0x protocol",
+    "main": "lib/src/index.js",
+    "directories": {
+        "test": "test"
+    },
+    "scripts": {
+        "build": "yarn pre_build && tsc -b",
+        "build:ci": "yarn build",
+        "pre_build": "run-s compile generate_contract_wrappers",
+        "test": "yarn run_mocha",
+        "rebuild_and_test": "run-s build test",
+        "test:coverage": "SOLIDITY_COVERAGE=true run-s build run_mocha coverage:report:text coverage:report:lcov",
+        "test:profiler": "SOLIDITY_PROFILER=true run-s build run_mocha profiler:report:html",
+        "test:trace": "SOLIDITY_REVERT_TRACE=true run-s build run_mocha",
+        "run_mocha":
+            "mocha --require source-map-support/register --require make-promises-safe 'lib/test/**/*.js' --timeout 100000 --bail --exit",
+        "compile": "sol-compiler --contracts-dir contracts",
+        "clean": "shx rm -rf lib generated-artifacts generated-wrappers",
+        "generate_contract_wrappers": "abi-gen --abis  ${npm_package_config_abis} --template ../../node_modules/@0x/abi-gen-templates/contract.handlebars --partials '../../node_modules/@0x/abi-gen-templates/partials/**/*.handlebars' --output generated-wrappers --backend ethers",
+        "lint": "tslint --format stylish --project . --exclude ./generated-wrappers/**/* --exclude ./generated-artifacts/**/* --exclude **/lib/**/* && yarn lint-contracts",
+        "coverage:report:text": "istanbul report text",
+        "coverage:report:html": "istanbul report html && open coverage/index.html",
+        "profiler:report:html": "istanbul report html && open coverage/index.html",
+        "coverage:report:lcov": "istanbul report lcov",
+        "test:circleci": "yarn test",
+        "lint-contracts": "solhint contracts/**/**/**/**/*.sol"
+    },
+    "config": {
+        "abis": "generated-artifacts/@(DutchAuction|Forwarder|OrderValidator).json"
+    },
+    "repository": {
+        "type": "git",
+        "url": "https://github.com/0xProject/0x-monorepo.git"
+    },
+    "license": "Apache-2.0",
+    "bugs": {
+        "url": "https://github.com/0xProject/0x-monorepo/issues"
+    },
+    "homepage": "https://github.com/0xProject/0x-monorepo/contracts/core/README.md",
+    "devDependencies": {
+        "@0x/contracts-test-utils": "^1.0.0",
+        "@0x/abi-gen": "^1.0.17",
+        "@0x/dev-utils": "^1.0.19",
+        "@0x/sol-compiler": "^1.1.14",
+        "@0x/sol-cov": "^2.1.14",
+        "@0x/subproviders": "^2.1.6",
+        "@0x/tslint-config": "^1.0.10",
+        "@types/bn.js": "^4.11.0",
+        "@types/lodash": "4.14.104",
+        "@types/node": "*",
+        "@types/yargs": "^10.0.0",
+        "chai": "^4.0.1",
+        "chai-as-promised": "^7.1.0",
+        "chai-bignumber": "^2.0.1",
+        "dirty-chai": "^2.0.1",
+        "make-promises-safe": "^1.1.0",
+        "ethereumjs-abi": "0.6.5",
+        "mocha": "^4.1.0",
+        "npm-run-all": "^4.1.2",
+        "shx": "^0.2.2",
+        "solc": "^0.4.24",
+        "solhint": "^1.2.1",
+        "tslint": "5.11.0",
+        "typescript": "3.0.1",
+        "yargs": "^10.0.3"
+    },
+    "dependencies": {
+        "@0x/base-contract": "^3.0.8",
+        "@0x/order-utils": "^3.0.4",
+        "@0x/contracts-utils": "^1.0.0",
+        "@0x/contracts-core": "^2.1.56",
+        "@0x/contracts-tokens": "^1.0.0",
+        "@0x/contracts-libs": "^1.0.0",
+        "@0x/contracts-interfaces": "^1.0.0",
+        "@0x/types": "^1.3.0",
+        "@0x/typescript-typings": "^3.0.4",
+        "@0x/utils": "^2.0.6",
+        "@0x/web3-wrapper": "^3.1.6",
+        "@types/js-combinatorics": "^0.5.29",
+        "bn.js": "^4.11.8",
+        "ethereum-types": "^1.1.2",
+        "ethereumjs-util": "^5.1.1",
+        "lodash": "^4.17.5"
+    },
+    "publishConfig": {
+        "access": "public"
+    }
+}
diff --git a/contracts/extensions/src/artifacts/index.ts b/contracts/extensions/src/artifacts/index.ts
new file mode 100644
index 000000000..380bf0497
--- /dev/null
+++ b/contracts/extensions/src/artifacts/index.ts
@@ -0,0 +1,11 @@
+import { ContractArtifact } from 'ethereum-types';
+
+import * as DutchAuction from '../../generated-artifacts/DutchAuction.json';
+import * as Forwarder from '../../generated-artifacts/Forwarder.json';
+import * as OrderValidator from '../../generated-artifacts/OrderValidator.json';
+
+export const artifacts = {
+    DutchAuction: DutchAuction as ContractArtifact,
+    Forwarder: Forwarder as ContractArtifact,
+    OrderValidator: OrderValidator as ContractArtifact,
+};
diff --git a/contracts/extensions/src/index.ts b/contracts/extensions/src/index.ts
new file mode 100644
index 000000000..d55f08ea2
--- /dev/null
+++ b/contracts/extensions/src/index.ts
@@ -0,0 +1,2 @@
+export * from './artifacts';
+export * from './wrappers';
diff --git a/contracts/extensions/src/wrappers/index.ts b/contracts/extensions/src/wrappers/index.ts
new file mode 100644
index 000000000..30f74b56e
--- /dev/null
+++ b/contracts/extensions/src/wrappers/index.ts
@@ -0,0 +1,3 @@
+export * from '../../generated-wrappers/dutch_auction';
+export * from '../../generated-wrappers/forwarder';
+export * from '../../generated-wrappers/order_validator';
diff --git a/contracts/core/test/extensions/dutch_auction.ts b/contracts/extensions/test/extensions/dutch_auction.ts
index b396d4206..2db3be752 100644
--- a/contracts/core/test/extensions/dutch_auction.ts
+++ b/contracts/extensions/test/extensions/dutch_auction.ts
@@ -1,4 +1,11 @@
 import {
+    artifacts as coreArtifacts,
+    ERC20Wrapper,
+    ERC721Wrapper,
+    ExchangeContract,
+    ExchangeWrapper,
+} from '@0x/contracts-core';
+import {
     chaiSetup,
     constants,
     ContractName,
@@ -27,11 +34,7 @@ import * as ethUtil from 'ethereumjs-util';
 import * as _ from 'lodash';
 
 import { DutchAuctionContract } from '../../generated-wrappers/dutch_auction';
-import { ExchangeContract } from '../../generated-wrappers/exchange';
 import { artifacts } from '../../src/artifacts';
-import { ERC20Wrapper } from '../utils/erc20_wrapper';
-import { ERC721Wrapper } from '../utils/erc721_wrapper';
-import { ExchangeWrapper } from '../utils/exchange_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -106,7 +109,7 @@ describe(ContractName.DutchAuction, () => {
 
         const zrxAssetData = assetDataUtils.encodeERC20AssetData(zrxToken.address);
         const exchangeInstance = await ExchangeContract.deployFrom0xArtifactAsync(
-            artifacts.Exchange,
+            coreArtifacts.Exchange,
             provider,
             txDefaults,
             zrxAssetData,
diff --git a/contracts/core/test/extensions/forwarder.ts b/contracts/extensions/test/extensions/forwarder.ts
index ffa015dd2..245d8eab9 100644
--- a/contracts/core/test/extensions/forwarder.ts
+++ b/contracts/extensions/test/extensions/forwarder.ts
@@ -1,4 +1,11 @@
 import {
+    artifacts as coreArtifacts,
+    ERC20Wrapper,
+    ERC721Wrapper,
+    ExchangeContract,
+    ExchangeWrapper,
+} from '@0x/contracts-core';
+import {
     chaiSetup,
     constants,
     ContractName,
@@ -25,12 +32,9 @@ import { Web3Wrapper } from '@0x/web3-wrapper';
 import * as chai from 'chai';
 import { TransactionReceiptWithDecodedLogs } from 'ethereum-types';
 
-import { ExchangeContract } from '../../generated-wrappers/exchange';
 import { ForwarderContract } from '../../generated-wrappers/forwarder';
 import { artifacts } from '../../src/artifacts';
-import { ERC20Wrapper } from '../utils/erc20_wrapper';
-import { ERC721Wrapper } from '../utils/erc721_wrapper';
-import { ExchangeWrapper } from '../utils/exchange_wrapper';
+
 import { ForwarderWrapper } from '../utils/forwarder_wrapper';
 
 chaiSetup.configure();
@@ -104,7 +108,7 @@ describe(ContractName.Forwarder, () => {
         wethAssetData = assetDataUtils.encodeERC20AssetData(wethContract.address);
         zrxAssetData = assetDataUtils.encodeERC20AssetData(zrxToken.address);
         const exchangeInstance = await ExchangeContract.deployFrom0xArtifactAsync(
-            artifacts.Exchange,
+            coreArtifacts.Exchange,
             provider,
             txDefaults,
             zrxAssetData,
@@ -175,7 +179,7 @@ describe(ContractName.Forwarder, () => {
     describe('constructor', () => {
         it('should revert if assetProxy is unregistered', async () => {
             const exchangeInstance = await ExchangeContract.deployFrom0xArtifactAsync(
-                artifacts.Exchange,
+                coreArtifacts.Exchange,
                 provider,
                 txDefaults,
                 zrxAssetData,
diff --git a/contracts/core/test/extensions/order_validator.ts b/contracts/extensions/test/extensions/order_validator.ts
index 622710c98..9a1dc0636 100644
--- a/contracts/core/test/extensions/order_validator.ts
+++ b/contracts/extensions/test/extensions/order_validator.ts
@@ -1,4 +1,13 @@
 import {
+    artifacts as coreArtifacts,
+    ERC20ProxyContract,
+    ERC20Wrapper,
+    ERC721ProxyContract,
+    ERC721Wrapper,
+    ExchangeContract,
+    ExchangeWrapper,
+} from '@0x/contracts-core';
+import {
     chaiSetup,
     constants,
     OrderFactory,
@@ -15,14 +24,8 @@ import { BigNumber } from '@0x/utils';
 import * as chai from 'chai';
 import * as _ from 'lodash';
 
-import { ERC20ProxyContract } from '../../generated-wrappers/erc20_proxy';
-import { ERC721ProxyContract } from '../../generated-wrappers/erc721_proxy';
-import { ExchangeContract } from '../../generated-wrappers/exchange';
 import { OrderValidatorContract } from '../../generated-wrappers/order_validator';
 import { artifacts } from '../../src/artifacts';
-import { ERC20Wrapper } from '../utils/erc20_wrapper';
-import { ERC721Wrapper } from '../utils/erc721_wrapper';
-import { ExchangeWrapper } from '../utils/exchange_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -78,7 +81,7 @@ describe('OrderValidator', () => {
 
         const zrxAssetData = assetDataUtils.encodeERC20AssetData(zrxToken.address);
         exchange = await ExchangeContract.deployFrom0xArtifactAsync(
-            artifacts.Exchange,
+            coreArtifacts.Exchange,
             provider,
             txDefaults,
             zrxAssetData,
diff --git a/contracts/extensions/test/global_hooks.ts b/contracts/extensions/test/global_hooks.ts
new file mode 100644
index 000000000..f8ace376a
--- /dev/null
+++ b/contracts/extensions/test/global_hooks.ts
@@ -0,0 +1,17 @@
+import { env, EnvVars } from '@0x/dev-utils';
+
+import { coverage, profiler, provider } from '@0x/contracts-test-utils';
+before('start web3 provider', () => {
+    provider.start();
+});
+after('generate coverage report', async () => {
+    if (env.parseBoolean(EnvVars.SolidityCoverage)) {
+        const coverageSubprovider = coverage.getCoverageSubproviderSingleton();
+        await coverageSubprovider.writeCoverageAsync();
+    }
+    if (env.parseBoolean(EnvVars.SolidityProfiler)) {
+        const profilerSubprovider = profiler.getProfilerSubproviderSingleton();
+        await profilerSubprovider.writeProfilerOutputAsync();
+    }
+    provider.stop();
+});
diff --git a/contracts/core/test/utils/forwarder_wrapper.ts b/contracts/extensions/test/utils/forwarder_wrapper.ts
index 4c78ecd79..4c78ecd79 100644
--- a/contracts/core/test/utils/forwarder_wrapper.ts
+++ b/contracts/extensions/test/utils/forwarder_wrapper.ts
diff --git a/contracts/extensions/tsconfig.json b/contracts/extensions/tsconfig.json
new file mode 100644
index 000000000..c894eb367
--- /dev/null
+++ b/contracts/extensions/tsconfig.json
@@ -0,0 +1,15 @@
+{
+    "extends": "../../tsconfig",
+    "compilerOptions": {
+        "outDir": "lib",
+        "rootDir": ".",
+        "resolveJsonModule": true
+    },
+    "include": ["./src/**/*", "./test/**/*", "./generated-wrappers/**/*"],
+    "files": [
+        "./generated-artifacts/DutchAuction.json",
+        "./generated-artifacts/Forwarder.json",
+        "./generated-artifacts/OrderValidator.json"
+    ],
+    "exclude": ["./deploy/solc/solc_bin"]
+}
diff --git a/contracts/extensions/tslint.json b/contracts/extensions/tslint.json
new file mode 100644
index 000000000..1bb3ac2a2
--- /dev/null
+++ b/contracts/extensions/tslint.json
@@ -0,0 +1,6 @@
+{
+    "extends": ["@0x/tslint-config"],
+    "rules": {
+        "custom-no-magic-numbers": false
+    }
+}