Split 0x.js into contract-wrappers, order-watcher but keep 0x.js as a unifying library with the same interface

17 files changed, 2543 insertions, 0 deletions

diff --git a/packages/order-watcher/src/artifacts.ts b/packages/order-watcher/src/artifacts.ts
new file mode 100644
index 000000000..13587984c
--- /dev/null
+++ b/packages/order-watcher/src/artifacts.ts
@@ -0,0 +1,18 @@
+import { Artifact } from '@0xproject/types';
+
+import * as DummyToken from './compact_artifacts/DummyToken.json';
+import * as EtherToken from './compact_artifacts/EtherToken.json';
+import * as Exchange from './compact_artifacts/Exchange.json';
+import * as Token from './compact_artifacts/Token.json';
+import * as TokenRegistry from './compact_artifacts/TokenRegistry.json';
+import * as TokenTransferProxy from './compact_artifacts/TokenTransferProxy.json';
+import * as ZRX from './compact_artifacts/ZRX.json';
+export const artifacts = {
+    ZRX: (ZRX as any) as Artifact,
+    DummyToken: (DummyToken as any) as Artifact,
+    Token: (Token as any) as Artifact,
+    Exchange: (Exchange as any) as Artifact,
+    EtherToken: (EtherToken as any) as Artifact,
+    TokenRegistry: (TokenRegistry as any) as Artifact,
+    TokenTransferProxy: (TokenTransferProxy as any) as Artifact,
+};
diff --git a/packages/order-watcher/src/compact_artifacts/DummyToken.json b/packages/order-watcher/src/compact_artifacts/DummyToken.json
new file mode 100644
index 000000000..f64a8cd3d
--- /dev/null
+++ b/packages/order-watcher/src/compact_artifacts/DummyToken.json
@@ -0,0 +1,22 @@
+{
+    "contract_name": "DummyToken",
+    "abi": [
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "_target",
+                    "type": "address"
+                },
+                {
+                    "name": "_value",
+                    "type": "uint256"
+                }
+            ],
+            "name": "setBalance",
+            "outputs": [],
+            "payable": false,
+            "type": "function"
+        }
+    ]
+}
diff --git a/packages/order-watcher/src/compact_artifacts/EtherToken.json b/packages/order-watcher/src/compact_artifacts/EtherToken.json
new file mode 100644
index 000000000..26cca57cd
--- /dev/null
+++ b/packages/order-watcher/src/compact_artifacts/EtherToken.json
@@ -0,0 +1,287 @@
+{
+    "contract_name": "EtherToken",
+    "abi": [
+        {
+            "constant": true,
+            "inputs": [],
+            "name": "name",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "string"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "_spender",
+                    "type": "address"
+                },
+                {
+                    "name": "_value",
+                    "type": "uint256"
+                }
+            ],
+            "name": "approve",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "bool"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [],
+            "name": "totalSupply",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "uint256"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "_from",
+                    "type": "address"
+                },
+                {
+                    "name": "_to",
+                    "type": "address"
+                },
+                {
+                    "name": "_value",
+                    "type": "uint256"
+                }
+            ],
+            "name": "transferFrom",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "bool"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "amount",
+                    "type": "uint256"
+                }
+            ],
+            "name": "withdraw",
+            "outputs": [],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [],
+            "name": "decimals",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "uint8"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "_owner",
+                    "type": "address"
+                }
+            ],
+            "name": "balanceOf",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "uint256"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [],
+            "name": "symbol",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "string"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "_to",
+                    "type": "address"
+                },
+                {
+                    "name": "_value",
+                    "type": "uint256"
+                }
+            ],
+            "name": "transfer",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "bool"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [],
+            "name": "deposit",
+            "outputs": [],
+            "payable": true,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "_owner",
+                    "type": "address"
+                },
+                {
+                    "name": "_spender",
+                    "type": "address"
+                }
+            ],
+            "name": "allowance",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "uint256"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "payable": true,
+            "type": "fallback"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "_from",
+                    "type": "address"
+                },
+                {
+                    "indexed": true,
+                    "name": "_to",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "_value",
+                    "type": "uint256"
+                }
+            ],
+            "name": "Transfer",
+            "type": "event"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "_owner",
+                    "type": "address"
+                },
+                {
+                    "indexed": true,
+                    "name": "_spender",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "_value",
+                    "type": "uint256"
+                }
+            ],
+            "name": "Approval",
+            "type": "event"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "_owner",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "_value",
+                    "type": "uint256"
+                }
+            ],
+            "name": "Deposit",
+            "type": "event"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "_owner",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "_value",
+                    "type": "uint256"
+                }
+            ],
+            "name": "Withdrawal",
+            "type": "event"
+        }
+    ],
+    "networks": {
+        "1": {
+            "address": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2"
+        },
+        "3": {
+            "address": "0xc00fd9820cd2898cc4c054b7bf142de637ad129a"
+        },
+        "4": {
+            "address": "0xc778417e063141139fce010982780140aa0cd5ab"
+        },
+        "42": {
+            "address": "0x653e49e301e508a13237c0ddc98ae7d4cd2667a1"
+        },
+        "50": {
+            "address": "0x871dd7c2b4b25e1aa18728e9d5f2af4c4e431f5c"
+        }
+    }
+}
diff --git a/packages/order-watcher/src/compact_artifacts/Exchange.json b/packages/order-watcher/src/compact_artifacts/Exchange.json
new file mode 100644
index 000000000..af8db7360
--- /dev/null
+++ b/packages/order-watcher/src/compact_artifacts/Exchange.json
@@ -0,0 +1,610 @@
+{
+    "contract_name": "Exchange",
+    "abi": [
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "numerator",
+                    "type": "uint256"
+                },
+                {
+                    "name": "denominator",
+                    "type": "uint256"
+                },
+                {
+                    "name": "target",
+                    "type": "uint256"
+                }
+            ],
+            "name": "isRoundingError",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "bool"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "",
+                    "type": "bytes32"
+                }
+            ],
+            "name": "filled",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "uint256"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "",
+                    "type": "bytes32"
+                }
+            ],
+            "name": "cancelled",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "uint256"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "orderAddresses",
+                    "type": "address[5][]"
+                },
+                {
+                    "name": "orderValues",
+                    "type": "uint256[6][]"
+                },
+                {
+                    "name": "fillTakerTokenAmount",
+                    "type": "uint256"
+                },
+                {
+                    "name": "shouldThrowOnInsufficientBalanceOrAllowance",
+                    "type": "bool"
+                },
+                {
+                    "name": "v",
+                    "type": "uint8[]"
+                },
+                {
+                    "name": "r",
+                    "type": "bytes32[]"
+                },
+                {
+                    "name": "s",
+                    "type": "bytes32[]"
+                }
+            ],
+            "name": "fillOrdersUpTo",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "uint256"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "orderAddresses",
+                    "type": "address[5]"
+                },
+                {
+                    "name": "orderValues",
+                    "type": "uint256[6]"
+                },
+                {
+                    "name": "cancelTakerTokenAmount",
+                    "type": "uint256"
+                }
+            ],
+            "name": "cancelOrder",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "uint256"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [],
+            "name": "ZRX_TOKEN_CONTRACT",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "address"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "orderAddresses",
+                    "type": "address[5][]"
+                },
+                {
+                    "name": "orderValues",
+                    "type": "uint256[6][]"
+                },
+                {
+                    "name": "fillTakerTokenAmounts",
+                    "type": "uint256[]"
+                },
+                {
+                    "name": "v",
+                    "type": "uint8[]"
+                },
+                {
+                    "name": "r",
+                    "type": "bytes32[]"
+                },
+                {
+                    "name": "s",
+                    "type": "bytes32[]"
+                }
+            ],
+            "name": "batchFillOrKillOrders",
+            "outputs": [],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "orderAddresses",
+                    "type": "address[5]"
+                },
+                {
+                    "name": "orderValues",
+                    "type": "uint256[6]"
+                },
+                {
+                    "name": "fillTakerTokenAmount",
+                    "type": "uint256"
+                },
+                {
+                    "name": "v",
+                    "type": "uint8"
+                },
+                {
+                    "name": "r",
+                    "type": "bytes32"
+                },
+                {
+                    "name": "s",
+                    "type": "bytes32"
+                }
+            ],
+            "name": "fillOrKillOrder",
+            "outputs": [],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "orderHash",
+                    "type": "bytes32"
+                }
+            ],
+            "name": "getUnavailableTakerTokenAmount",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "uint256"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "signer",
+                    "type": "address"
+                },
+                {
+                    "name": "hash",
+                    "type": "bytes32"
+                },
+                {
+                    "name": "v",
+                    "type": "uint8"
+                },
+                {
+                    "name": "r",
+                    "type": "bytes32"
+                },
+                {
+                    "name": "s",
+                    "type": "bytes32"
+                }
+            ],
+            "name": "isValidSignature",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "bool"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "numerator",
+                    "type": "uint256"
+                },
+                {
+                    "name": "denominator",
+                    "type": "uint256"
+                },
+                {
+                    "name": "target",
+                    "type": "uint256"
+                }
+            ],
+            "name": "getPartialAmount",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "uint256"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [],
+            "name": "TOKEN_TRANSFER_PROXY_CONTRACT",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "address"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "orderAddresses",
+                    "type": "address[5][]"
+                },
+                {
+                    "name": "orderValues",
+                    "type": "uint256[6][]"
+                },
+                {
+                    "name": "fillTakerTokenAmounts",
+                    "type": "uint256[]"
+                },
+                {
+                    "name": "shouldThrowOnInsufficientBalanceOrAllowance",
+                    "type": "bool"
+                },
+                {
+                    "name": "v",
+                    "type": "uint8[]"
+                },
+                {
+                    "name": "r",
+                    "type": "bytes32[]"
+                },
+                {
+                    "name": "s",
+                    "type": "bytes32[]"
+                }
+            ],
+            "name": "batchFillOrders",
+            "outputs": [],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "orderAddresses",
+                    "type": "address[5][]"
+                },
+                {
+                    "name": "orderValues",
+                    "type": "uint256[6][]"
+                },
+                {
+                    "name": "cancelTakerTokenAmounts",
+                    "type": "uint256[]"
+                }
+            ],
+            "name": "batchCancelOrders",
+            "outputs": [],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "orderAddresses",
+                    "type": "address[5]"
+                },
+                {
+                    "name": "orderValues",
+                    "type": "uint256[6]"
+                },
+                {
+                    "name": "fillTakerTokenAmount",
+                    "type": "uint256"
+                },
+                {
+                    "name": "shouldThrowOnInsufficientBalanceOrAllowance",
+                    "type": "bool"
+                },
+                {
+                    "name": "v",
+                    "type": "uint8"
+                },
+                {
+                    "name": "r",
+                    "type": "bytes32"
+                },
+                {
+                    "name": "s",
+                    "type": "bytes32"
+                }
+            ],
+            "name": "fillOrder",
+            "outputs": [
+                {
+                    "name": "filledTakerTokenAmount",
+                    "type": "uint256"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "orderAddresses",
+                    "type": "address[5]"
+                },
+                {
+                    "name": "orderValues",
+                    "type": "uint256[6]"
+                }
+            ],
+            "name": "getOrderHash",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "bytes32"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [],
+            "name": "EXTERNAL_QUERY_GAS_LIMIT",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "uint16"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [],
+            "name": "VERSION",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "string"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "inputs": [
+                {
+                    "name": "_zrxToken",
+                    "type": "address"
+                },
+                {
+                    "name": "_tokenTransferProxy",
+                    "type": "address"
+                }
+            ],
+            "payable": false,
+            "type": "constructor"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "maker",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "taker",
+                    "type": "address"
+                },
+                {
+                    "indexed": true,
+                    "name": "feeRecipient",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "makerToken",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "takerToken",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "filledMakerTokenAmount",
+                    "type": "uint256"
+                },
+                {
+                    "indexed": false,
+                    "name": "filledTakerTokenAmount",
+                    "type": "uint256"
+                },
+                {
+                    "indexed": false,
+                    "name": "paidMakerFee",
+                    "type": "uint256"
+                },
+                {
+                    "indexed": false,
+                    "name": "paidTakerFee",
+                    "type": "uint256"
+                },
+                {
+                    "indexed": true,
+                    "name": "tokens",
+                    "type": "bytes32"
+                },
+                {
+                    "indexed": false,
+                    "name": "orderHash",
+                    "type": "bytes32"
+                }
+            ],
+            "name": "LogFill",
+            "type": "event"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "maker",
+                    "type": "address"
+                },
+                {
+                    "indexed": true,
+                    "name": "feeRecipient",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "makerToken",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "takerToken",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "cancelledMakerTokenAmount",
+                    "type": "uint256"
+                },
+                {
+                    "indexed": false,
+                    "name": "cancelledTakerTokenAmount",
+                    "type": "uint256"
+                },
+                {
+                    "indexed": true,
+                    "name": "tokens",
+                    "type": "bytes32"
+                },
+                {
+                    "indexed": false,
+                    "name": "orderHash",
+                    "type": "bytes32"
+                }
+            ],
+            "name": "LogCancel",
+            "type": "event"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "errorId",
+                    "type": "uint8"
+                },
+                {
+                    "indexed": true,
+                    "name": "orderHash",
+                    "type": "bytes32"
+                }
+            ],
+            "name": "LogError",
+            "type": "event"
+        }
+    ],
+    "networks": {
+        "1": {
+            "address": "0x12459c951127e0c374ff9105dda097662a027093"
+        },
+        "3": {
+            "address": "0x479cc461fecd078f766ecc58533d6f69580cf3ac"
+        },
+        "4": {
+            "address": "0x1d16ef40fac01cec8adac2ac49427b9384192c05"
+        },
+        "42": {
+            "address": "0x90fe2af704b34e0224bf2299c838e04d4dcf1364"
+        },
+        "50": {
+            "address": "0x48bacb9266a570d521063ef5dd96e61686dbe788"
+        }
+    }
+}
diff --git a/packages/order-watcher/src/compact_artifacts/Token.json b/packages/order-watcher/src/compact_artifacts/Token.json
new file mode 100644
index 000000000..3b5a86ae0
--- /dev/null
+++ b/packages/order-watcher/src/compact_artifacts/Token.json
@@ -0,0 +1,172 @@
+{
+    "contract_name": "Token",
+    "abi": [
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "_spender",
+                    "type": "address"
+                },
+                {
+                    "name": "_value",
+                    "type": "uint256"
+                }
+            ],
+            "name": "approve",
+            "outputs": [
+                {
+                    "name": "success",
+                    "type": "bool"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [],
+            "name": "totalSupply",
+            "outputs": [
+                {
+                    "name": "supply",
+                    "type": "uint256"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "_from",
+                    "type": "address"
+                },
+                {
+                    "name": "_to",
+                    "type": "address"
+                },
+                {
+                    "name": "_value",
+                    "type": "uint256"
+                }
+            ],
+            "name": "transferFrom",
+            "outputs": [
+                {
+                    "name": "success",
+                    "type": "bool"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "_owner",
+                    "type": "address"
+                }
+            ],
+            "name": "balanceOf",
+            "outputs": [
+                {
+                    "name": "balance",
+                    "type": "uint256"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "_to",
+                    "type": "address"
+                },
+                {
+                    "name": "_value",
+                    "type": "uint256"
+                }
+            ],
+            "name": "transfer",
+            "outputs": [
+                {
+                    "name": "success",
+                    "type": "bool"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "_owner",
+                    "type": "address"
+                },
+                {
+                    "name": "_spender",
+                    "type": "address"
+                }
+            ],
+            "name": "allowance",
+            "outputs": [
+                {
+                    "name": "remaining",
+                    "type": "uint256"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "_from",
+                    "type": "address"
+                },
+                {
+                    "indexed": true,
+                    "name": "_to",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "_value",
+                    "type": "uint256"
+                }
+            ],
+            "name": "Transfer",
+            "type": "event"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "_owner",
+                    "type": "address"
+                },
+                {
+                    "indexed": true,
+                    "name": "_spender",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "_value",
+                    "type": "uint256"
+                }
+            ],
+            "name": "Approval",
+            "type": "event"
+        }
+    ]
+}
diff --git a/packages/order-watcher/src/compact_artifacts/TokenRegistry.json b/packages/order-watcher/src/compact_artifacts/TokenRegistry.json
new file mode 100644
index 000000000..0f583628c
--- /dev/null
+++ b/packages/order-watcher/src/compact_artifacts/TokenRegistry.json
@@ -0,0 +1,547 @@
+{
+    "contract_name": "TokenRegistry",
+    "abi": [
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "_token",
+                    "type": "address"
+                },
+                {
+                    "name": "_index",
+                    "type": "uint256"
+                }
+            ],
+            "name": "removeToken",
+            "outputs": [],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "_name",
+                    "type": "string"
+                }
+            ],
+            "name": "getTokenAddressByName",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "address"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "_symbol",
+                    "type": "string"
+                }
+            ],
+            "name": "getTokenAddressBySymbol",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "address"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "_token",
+                    "type": "address"
+                },
+                {
+                    "name": "_swarmHash",
+                    "type": "bytes"
+                }
+            ],
+            "name": "setTokenSwarmHash",
+            "outputs": [],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "_token",
+                    "type": "address"
+                }
+            ],
+            "name": "getTokenMetaData",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "address"
+                },
+                {
+                    "name": "",
+                    "type": "string"
+                },
+                {
+                    "name": "",
+                    "type": "string"
+                },
+                {
+                    "name": "",
+                    "type": "uint8"
+                },
+                {
+                    "name": "",
+                    "type": "bytes"
+                },
+                {
+                    "name": "",
+                    "type": "bytes"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [],
+            "name": "owner",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "address"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "_token",
+                    "type": "address"
+                },
+                {
+                    "name": "_name",
+                    "type": "string"
+                },
+                {
+                    "name": "_symbol",
+                    "type": "string"
+                },
+                {
+                    "name": "_decimals",
+                    "type": "uint8"
+                },
+                {
+                    "name": "_ipfsHash",
+                    "type": "bytes"
+                },
+                {
+                    "name": "_swarmHash",
+                    "type": "bytes"
+                }
+            ],
+            "name": "addToken",
+            "outputs": [],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "_token",
+                    "type": "address"
+                },
+                {
+                    "name": "_name",
+                    "type": "string"
+                }
+            ],
+            "name": "setTokenName",
+            "outputs": [],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "",
+                    "type": "address"
+                }
+            ],
+            "name": "tokens",
+            "outputs": [
+                {
+                    "name": "token",
+                    "type": "address"
+                },
+                {
+                    "name": "name",
+                    "type": "string"
+                },
+                {
+                    "name": "symbol",
+                    "type": "string"
+                },
+                {
+                    "name": "decimals",
+                    "type": "uint8"
+                },
+                {
+                    "name": "ipfsHash",
+                    "type": "bytes"
+                },
+                {
+                    "name": "swarmHash",
+                    "type": "bytes"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "",
+                    "type": "uint256"
+                }
+            ],
+            "name": "tokenAddresses",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "address"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "_name",
+                    "type": "string"
+                }
+            ],
+            "name": "getTokenByName",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "address"
+                },
+                {
+                    "name": "",
+                    "type": "string"
+                },
+                {
+                    "name": "",
+                    "type": "string"
+                },
+                {
+                    "name": "",
+                    "type": "uint8"
+                },
+                {
+                    "name": "",
+                    "type": "bytes"
+                },
+                {
+                    "name": "",
+                    "type": "bytes"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [],
+            "name": "getTokenAddresses",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "address[]"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "_token",
+                    "type": "address"
+                },
+                {
+                    "name": "_ipfsHash",
+                    "type": "bytes"
+                }
+            ],
+            "name": "setTokenIpfsHash",
+            "outputs": [],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "_symbol",
+                    "type": "string"
+                }
+            ],
+            "name": "getTokenBySymbol",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "address"
+                },
+                {
+                    "name": "",
+                    "type": "string"
+                },
+                {
+                    "name": "",
+                    "type": "string"
+                },
+                {
+                    "name": "",
+                    "type": "uint8"
+                },
+                {
+                    "name": "",
+                    "type": "bytes"
+                },
+                {
+                    "name": "",
+                    "type": "bytes"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "_token",
+                    "type": "address"
+                },
+                {
+                    "name": "_symbol",
+                    "type": "string"
+                }
+            ],
+            "name": "setTokenSymbol",
+            "outputs": [],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "newOwner",
+                    "type": "address"
+                }
+            ],
+            "name": "transferOwnership",
+            "outputs": [],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "token",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "name",
+                    "type": "string"
+                },
+                {
+                    "indexed": false,
+                    "name": "symbol",
+                    "type": "string"
+                },
+                {
+                    "indexed": false,
+                    "name": "decimals",
+                    "type": "uint8"
+                },
+                {
+                    "indexed": false,
+                    "name": "ipfsHash",
+                    "type": "bytes"
+                },
+                {
+                    "indexed": false,
+                    "name": "swarmHash",
+                    "type": "bytes"
+                }
+            ],
+            "name": "LogAddToken",
+            "type": "event"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "token",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "name",
+                    "type": "string"
+                },
+                {
+                    "indexed": false,
+                    "name": "symbol",
+                    "type": "string"
+                },
+                {
+                    "indexed": false,
+                    "name": "decimals",
+                    "type": "uint8"
+                },
+                {
+                    "indexed": false,
+                    "name": "ipfsHash",
+                    "type": "bytes"
+                },
+                {
+                    "indexed": false,
+                    "name": "swarmHash",
+                    "type": "bytes"
+                }
+            ],
+            "name": "LogRemoveToken",
+            "type": "event"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "token",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "oldName",
+                    "type": "string"
+                },
+                {
+                    "indexed": false,
+                    "name": "newName",
+                    "type": "string"
+                }
+            ],
+            "name": "LogTokenNameChange",
+            "type": "event"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "token",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "oldSymbol",
+                    "type": "string"
+                },
+                {
+                    "indexed": false,
+                    "name": "newSymbol",
+                    "type": "string"
+                }
+            ],
+            "name": "LogTokenSymbolChange",
+            "type": "event"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "token",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "oldIpfsHash",
+                    "type": "bytes"
+                },
+                {
+                    "indexed": false,
+                    "name": "newIpfsHash",
+                    "type": "bytes"
+                }
+            ],
+            "name": "LogTokenIpfsHashChange",
+            "type": "event"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "token",
+                    "type": "address"
+                },
+                {
+                    "indexed": false,
+                    "name": "oldSwarmHash",
+                    "type": "bytes"
+                },
+                {
+                    "indexed": false,
+                    "name": "newSwarmHash",
+                    "type": "bytes"
+                }
+            ],
+            "name": "LogTokenSwarmHashChange",
+            "type": "event"
+        }
+    ],
+    "networks": {
+        "1": {
+            "address": "0x926a74c5c36adf004c87399e65f75628b0f98d2c"
+        },
+        "3": {
+            "address": "0x6b1a50f0bb5a7995444bd3877b22dc89c62843ed"
+        },
+        "4": {
+            "address": "0x4e9aad8184de8833365fea970cd9149372fdf1e6"
+        },
+        "42": {
+            "address": "0xf18e504561f4347bea557f3d4558f559dddbae7f"
+        },
+        "50": {
+            "address": "0x0b1ba0af832d7c05fd64161e0db78e85978e8082"
+        }
+    }
+}
diff --git a/packages/order-watcher/src/compact_artifacts/TokenTransferProxy.json b/packages/order-watcher/src/compact_artifacts/TokenTransferProxy.json
new file mode 100644
index 000000000..8cf551ddb
--- /dev/null
+++ b/packages/order-watcher/src/compact_artifacts/TokenTransferProxy.json
@@ -0,0 +1,187 @@
+{
+    "contract_name": "TokenTransferProxy",
+    "abi": [
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "token",
+                    "type": "address"
+                },
+                {
+                    "name": "from",
+                    "type": "address"
+                },
+                {
+                    "name": "to",
+                    "type": "address"
+                },
+                {
+                    "name": "value",
+                    "type": "uint256"
+                }
+            ],
+            "name": "transferFrom",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "bool"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "target",
+                    "type": "address"
+                }
+            ],
+            "name": "addAuthorizedAddress",
+            "outputs": [],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "",
+                    "type": "uint256"
+                }
+            ],
+            "name": "authorities",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "address"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "target",
+                    "type": "address"
+                }
+            ],
+            "name": "removeAuthorizedAddress",
+            "outputs": [],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [],
+            "name": "owner",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "address"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [
+                {
+                    "name": "",
+                    "type": "address"
+                }
+            ],
+            "name": "authorized",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "bool"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": true,
+            "inputs": [],
+            "name": "getAuthorizedAddresses",
+            "outputs": [
+                {
+                    "name": "",
+                    "type": "address[]"
+                }
+            ],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "constant": false,
+            "inputs": [
+                {
+                    "name": "newOwner",
+                    "type": "address"
+                }
+            ],
+            "name": "transferOwnership",
+            "outputs": [],
+            "payable": false,
+            "type": "function"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "target",
+                    "type": "address"
+                },
+                {
+                    "indexed": true,
+                    "name": "caller",
+                    "type": "address"
+                }
+            ],
+            "name": "LogAuthorizedAddressAdded",
+            "type": "event"
+        },
+        {
+            "anonymous": false,
+            "inputs": [
+                {
+                    "indexed": true,
+                    "name": "target",
+                    "type": "address"
+                },
+                {
+                    "indexed": true,
+                    "name": "caller",
+                    "type": "address"
+                }
+            ],
+            "name": "LogAuthorizedAddressRemoved",
+            "type": "event"
+        }
+    ],
+    "networks": {
+        "1": {
+            "address": "0x8da0d80f5007ef1e431dd2127178d224e32c2ef4"
+        },
+        "3": {
+            "address": "0x4e9aad8184de8833365fea970cd9149372fdf1e6"
+        },
+        "4": {
+            "address": "0xa8e9fa8f91e5ae138c74648c9c304f1c75003a8d"
+        },
+        "42": {
+            "address": "0x087eed4bc1ee3de49befbd66c662b434b15d49d4"
+        },
+        "50": {
+            "address": "0x1dc4c1cefef38a777b15aa20260a54e584b16c48"
+        }
+    }
+}
diff --git a/packages/order-watcher/src/compact_artifacts/ZRX.json b/packages/order-watcher/src/compact_artifacts/ZRX.json
new file mode 100644
index 000000000..e40b8f268
--- /dev/null
+++ b/packages/order-watcher/src/compact_artifacts/ZRX.json
@@ -0,0 +1,20 @@
+{
+    "contract_name": "ZRX",
+    "networks": {
+        "1": {
+            "address": "0xe41d2489571d322189246dafa5ebde1f4699f498"
+        },
+        "3": {
+            "address": "0xa8e9fa8f91e5ae138c74648c9c304f1c75003a8d"
+        },
+        "4": {
+            "address": "0x00f58d6d585f84b2d7267940cede30ce2fe6eae8"
+        },
+        "42": {
+            "address": "0x6ff6c0ff1d68b964901f986d4c9fa3ac68346570"
+        },
+        "50": {
+            "address": "0x1d7022f5b17d2f8b695918fb48fa1089c9f85401"
+        }
+    }
+}
diff --git a/packages/order-watcher/src/globals.d.ts b/packages/order-watcher/src/globals.d.ts
new file mode 100644
index 000000000..94e63a32d
--- /dev/null
+++ b/packages/order-watcher/src/globals.d.ts
@@ -0,0 +1,6 @@
+declare module '*.json' {
+    const json: any;
+    /* tslint:disable */
+    export default json;
+    /* tslint:enable */
+}
diff --git a/packages/order-watcher/src/index.ts b/packages/order-watcher/src/index.ts
new file mode 100644
index 000000000..390003b1d
--- /dev/null
+++ b/packages/order-watcher/src/index.ts
@@ -0,0 +1,7 @@
+export { OrderWatcher } from './order_watcher/order_watcher';
+
+export { OrderStateValid, OrderStateInvalid, OrderState } from '@0xproject/types';
+
+export { OnOrderStateChangeCallback, OrderWatcherConfig } from './types';
+
+export { BlockParamLiteral, BlockParam, Order, Provider, SignedOrder } from '@0xproject/types';
diff --git a/packages/order-watcher/src/monorepo_scripts/postpublish.ts b/packages/order-watcher/src/monorepo_scripts/postpublish.ts
new file mode 100644
index 000000000..dcb99d0f7
--- /dev/null
+++ b/packages/order-watcher/src/monorepo_scripts/postpublish.ts
@@ -0,0 +1,8 @@
+import { postpublishUtils } from '@0xproject/monorepo-scripts';
+
+import * as packageJSON from '../package.json';
+import * as tsConfigJSON from '../tsconfig.json';
+
+const cwd = `${__dirname}/..`;
+// tslint:disable-next-line:no-floating-promises
+postpublishUtils.runAsync(packageJSON, tsConfigJSON, cwd);
diff --git a/packages/order-watcher/src/order_watcher/event_watcher.ts b/packages/order-watcher/src/order_watcher/event_watcher.ts
new file mode 100644
index 000000000..f39d3bf0e
--- /dev/null
+++ b/packages/order-watcher/src/order_watcher/event_watcher.ts
@@ -0,0 +1,99 @@
+import { BlockParamLiteral, LogEntry } from '@0xproject/types';
+import { intervalUtils } from '@0xproject/utils';
+import { Web3Wrapper } from '@0xproject/web3-wrapper';
+import * as _ from 'lodash';
+
+import { EventWatcherCallback, OrderWatcherError } from '../types';
+import { assert } from '../utils/assert';
+
+const DEFAULT_EVENT_POLLING_INTERVAL_MS = 200;
+
+enum LogEventState {
+    Removed,
+    Added,
+}
+
+/**
+ * The EventWatcher watches for blockchain events at the specified block confirmation
+ * depth.
+ */
+export class EventWatcher {
+    private _web3Wrapper: Web3Wrapper;
+    private _pollingIntervalMs: number;
+    private _intervalIdIfExists?: NodeJS.Timer;
+    private _lastEvents: LogEntry[] = [];
+    private _stateLayer: BlockParamLiteral;
+    constructor(
+        web3Wrapper: Web3Wrapper,
+        pollingIntervalIfExistsMs: undefined | number,
+        stateLayer: BlockParamLiteral = BlockParamLiteral.Latest,
+    ) {
+        this._web3Wrapper = web3Wrapper;
+        this._stateLayer = stateLayer;
+        this._pollingIntervalMs = _.isUndefined(pollingIntervalIfExistsMs)
+            ? DEFAULT_EVENT_POLLING_INTERVAL_MS
+            : pollingIntervalIfExistsMs;
+    }
+    public subscribe(callback: EventWatcherCallback): void {
+        assert.isFunction('callback', callback);
+        if (!_.isUndefined(this._intervalIdIfExists)) {
+            throw new Error(OrderWatcherError.SubscriptionAlreadyPresent);
+        }
+        this._intervalIdIfExists = intervalUtils.setAsyncExcludingInterval(
+            this._pollForBlockchainEventsAsync.bind(this, callback),
+            this._pollingIntervalMs,
+            (err: Error) => {
+                this.unsubscribe();
+                callback(err);
+            },
+        );
+    }
+    public unsubscribe(): void {
+        this._lastEvents = [];
+        if (!_.isUndefined(this._intervalIdIfExists)) {
+            intervalUtils.clearAsyncExcludingInterval(this._intervalIdIfExists);
+            delete this._intervalIdIfExists;
+        }
+    }
+    private async _pollForBlockchainEventsAsync(callback: EventWatcherCallback): Promise<void> {
+        const pendingEvents = await this._getEventsAsync();
+        if (_.isUndefined(pendingEvents)) {
+            // HACK: This should never happen, but happens frequently on CI due to a ganache bug
+            return;
+        }
+        if (pendingEvents.length === 0) {
+            // HACK: Sometimes when node rebuilds the pending block we get back the empty result.
+            // We don't want to emit a lot of removal events and bring them back after a couple of miliseconds,
+            // that's why we just ignore those cases.
+            return;
+        }
+        const removedEvents = _.differenceBy(this._lastEvents, pendingEvents, JSON.stringify);
+        const newEvents = _.differenceBy(pendingEvents, this._lastEvents, JSON.stringify);
+        await this._emitDifferencesAsync(removedEvents, LogEventState.Removed, callback);
+        await this._emitDifferencesAsync(newEvents, LogEventState.Added, callback);
+        this._lastEvents = pendingEvents;
+    }
+    private async _getEventsAsync(): Promise<LogEntry[]> {
+        const eventFilter = {
+            fromBlock: this._stateLayer,
+            toBlock: this._stateLayer,
+        };
+        const events = await this._web3Wrapper.getLogsAsync(eventFilter);
+        return events;
+    }
+    private async _emitDifferencesAsync(
+        logs: LogEntry[],
+        logEventState: LogEventState,
+        callback: EventWatcherCallback,
+    ): Promise<void> {
+        for (const log of logs) {
+            const logEvent = {
+                removed: logEventState === LogEventState.Removed,
+                ...log,
+            };
+            if (!_.isUndefined(this._intervalIdIfExists)) {
+                callback(null, logEvent);
+            }
+        }
+    }
+}
diff --git a/packages/order-watcher/src/order_watcher/expiration_watcher.ts b/packages/order-watcher/src/order_watcher/expiration_watcher.ts
new file mode 100644
index 000000000..ec2c1ec35
--- /dev/null
+++ b/packages/order-watcher/src/order_watcher/expiration_watcher.ts
@@ -0,0 +1,87 @@
+import { BigNumber, intervalUtils } from '@0xproject/utils';
+import { RBTree } from 'bintrees';
+import * as _ from 'lodash';
+
+import { OrderWatcherError } from '../types';
+import { utils } from '../utils/utils';
+
+const DEFAULT_EXPIRATION_MARGIN_MS = 0;
+const DEFAULT_ORDER_EXPIRATION_CHECKING_INTERVAL_MS = 50;
+
+/**
+ * This class includes the functionality to detect expired orders.
+ * It stores them in a min heap by expiration time and checks for expired ones every `orderExpirationCheckingIntervalMs`
+ */
+export class ExpirationWatcher {
+    private _orderHashByExpirationRBTree: RBTree<string>;
+    private _expiration: { [orderHash: string]: BigNumber } = {};
+    private _orderExpirationCheckingIntervalMs: number;
+    private _expirationMarginMs: number;
+    private _orderExpirationCheckingIntervalIdIfExists?: NodeJS.Timer;
+    constructor(expirationMarginIfExistsMs?: number, orderExpirationCheckingIntervalIfExistsMs?: number) {
+        this._expirationMarginMs = expirationMarginIfExistsMs || DEFAULT_EXPIRATION_MARGIN_MS;
+        this._orderExpirationCheckingIntervalMs =
+            expirationMarginIfExistsMs || DEFAULT_ORDER_EXPIRATION_CHECKING_INTERVAL_MS;
+        const comparator = (lhsOrderHash: string, rhsOrderHash: string) => {
+            const lhsExpiration = this._expiration[lhsOrderHash].toNumber();
+            const rhsExpiration = this._expiration[rhsOrderHash].toNumber();
+            if (lhsExpiration !== rhsExpiration) {
+                return lhsExpiration - rhsExpiration;
+            } else {
+                // HACK: If two orders have identical expirations, the order in which they are emitted by the
+                // ExpirationWatcher does not matter, so we emit them in alphabetical order by orderHash.
+                return lhsOrderHash.localeCompare(rhsOrderHash);
+            }
+        };
+        this._orderHashByExpirationRBTree = new RBTree(comparator);
+    }
+    public subscribe(callback: (orderHash: string) => void): void {
+        if (!_.isUndefined(this._orderExpirationCheckingIntervalIdIfExists)) {
+            throw new Error(OrderWatcherError.SubscriptionAlreadyPresent);
+        }
+        this._orderExpirationCheckingIntervalIdIfExists = intervalUtils.setInterval(
+            this._pruneExpiredOrders.bind(this, callback),
+            this._orderExpirationCheckingIntervalMs,
+            _.noop, // _pruneExpiredOrders never throws
+        );
+    }
+    public unsubscribe(): void {
+        if (_.isUndefined(this._orderExpirationCheckingIntervalIdIfExists)) {
+            throw new Error(OrderWatcherError.SubscriptionNotFound);
+        }
+        intervalUtils.clearInterval(this._orderExpirationCheckingIntervalIdIfExists);
+        delete this._orderExpirationCheckingIntervalIdIfExists;
+    }
+    public addOrder(orderHash: string, expirationUnixTimestampMs: BigNumber): void {
+        this._expiration[orderHash] = expirationUnixTimestampMs;
+        this._orderHashByExpirationRBTree.insert(orderHash);
+    }
+    public removeOrder(orderHash: string): void {
+        if (_.isUndefined(this._expiration[orderHash])) {
+            return; // noop since order already removed
+        }
+        this._orderHashByExpirationRBTree.remove(orderHash);
+        delete this._expiration[orderHash];
+    }
+    private _pruneExpiredOrders(callback: (orderHash: string) => void): void {
+        const currentUnixTimestampMs = utils.getCurrentUnixTimestampMs();
+        while (true) {
+            const hasTrakedOrders = this._orderHashByExpirationRBTree.size === 0;
+            if (hasTrakedOrders) {
+                break;
+            }
+            const nextOrderHashToExpire = this._orderHashByExpirationRBTree.min();
+            const hasNoExpiredOrders = this._expiration[nextOrderHashToExpire].greaterThan(
+                currentUnixTimestampMs.plus(this._expirationMarginMs),
+            );
+            const isSubscriptionActive = _.isUndefined(this._orderExpirationCheckingIntervalIdIfExists);
+            if (hasNoExpiredOrders || isSubscriptionActive) {
+                break;
+            }
+            const orderHash = this._orderHashByExpirationRBTree.min();
+            this._orderHashByExpirationRBTree.remove(orderHash);
+            delete this._expiration[orderHash];
+            callback(orderHash);
+        }
+    }
+}
diff --git a/packages/order-watcher/src/order_watcher/order_watcher.ts b/packages/order-watcher/src/order_watcher/order_watcher.ts
new file mode 100644
index 000000000..63f87b565
--- /dev/null
+++ b/packages/order-watcher/src/order_watcher/order_watcher.ts
@@ -0,0 +1,393 @@
+import {
+    BalanceAndProxyAllowanceLazyStore,
+    ContractWrappers,
+    OrderFilledCancelledLazyStore,
+} from '@0xproject/contract-wrappers';
+import { schemas } from '@0xproject/json-schemas';
+import { getOrderHashHex, OrderStateUtils } from '@0xproject/order-utils';
+import {
+    BlockParamLiteral,
+    ExchangeContractErrs,
+    LogEntryEvent,
+    LogWithDecodedArgs,
+    OrderState,
+    Provider,
+    SignedOrder,
+} from '@0xproject/types';
+import { AbiDecoder, intervalUtils } from '@0xproject/utils';
+import { Web3Wrapper } from '@0xproject/web3-wrapper';
+import * as _ from 'lodash';
+
+import { artifacts } from '../artifacts';
+import {
+    DepositContractEventArgs,
+    EtherTokenContractEventArgs,
+    EtherTokenEvents,
+    WithdrawalContractEventArgs,
+} from '../generated_contract_wrappers/ether_token';
+import {
+    ExchangeContractEventArgs,
+    ExchangeEvents,
+    LogCancelContractEventArgs,
+    LogFillContractEventArgs,
+} from '../generated_contract_wrappers/exchange';
+import {
+    ApprovalContractEventArgs,
+    TokenContractEventArgs,
+    TokenEvents,
+    TransferContractEventArgs,
+} from '../generated_contract_wrappers/token';
+import { OnOrderStateChangeCallback, OrderWatcherConfig, OrderWatcherError } from '../types';
+import { assert } from '../utils/assert';
+import { utils } from '../utils/utils';
+
+import { EventWatcher } from './event_watcher';
+import { ExpirationWatcher } from './expiration_watcher';
+
+type ContractEventArgs = EtherTokenContractEventArgs | ExchangeContractEventArgs | TokenContractEventArgs;
+
+interface DependentOrderHashes {
+    [makerAddress: string]: {
+        [makerToken: string]: Set<string>;
+    };
+}
+
+interface OrderByOrderHash {
+    [orderHash: string]: SignedOrder;
+}
+
+interface OrderStateByOrderHash {
+    [orderHash: string]: OrderState;
+}
+
+const DEFAULT_CLEANUP_JOB_INTERVAL_MS = 1000 * 60 * 60; // 1h
+
+/**
+ * This class includes all the functionality related to watching a set of orders
+ * for potential changes in order validity/fillability. The orderWatcher notifies
+ * the subscriber of these changes so that a final decision can be made on whether
+ * the order should be deemed invalid.
+ */
+export class OrderWatcher {
+    private _contractWrappers: ContractWrappers;
+    private _orderStateByOrderHashCache: OrderStateByOrderHash = {};
+    private _orderByOrderHash: OrderByOrderHash = {};
+    private _dependentOrderHashes: DependentOrderHashes = {};
+    private _callbackIfExists?: OnOrderStateChangeCallback;
+    private _eventWatcher: EventWatcher;
+    private _web3Wrapper: Web3Wrapper;
+    private _expirationWatcher: ExpirationWatcher;
+    private _orderStateUtils: OrderStateUtils;
+    private _orderFilledCancelledLazyStore: OrderFilledCancelledLazyStore;
+    private _balanceAndProxyAllowanceLazyStore: BalanceAndProxyAllowanceLazyStore;
+    private _cleanupJobInterval: number;
+    private _cleanupJobIntervalIdIfExists?: NodeJS.Timer;
+    constructor(provider: Provider, networkId: number, config?: OrderWatcherConfig) {
+        this._web3Wrapper = new Web3Wrapper(provider);
+        const artifactJSONs = _.values(artifacts);
+        const abiArrays = _.map(artifactJSONs, artifact => artifact.abi);
+        _.forEach(abiArrays, abi => {
+            this._web3Wrapper.abiDecoder.addABI(abi);
+        });
+        this._contractWrappers = new ContractWrappers(provider, { networkId });
+        const pollingIntervalIfExistsMs = _.isUndefined(config) ? undefined : config.eventPollingIntervalMs;
+        const stateLayer =
+            _.isUndefined(config) || _.isUndefined(config.stateLayer) ? BlockParamLiteral.Latest : config.stateLayer;
+        this._eventWatcher = new EventWatcher(this._web3Wrapper, pollingIntervalIfExistsMs, stateLayer);
+        this._balanceAndProxyAllowanceLazyStore = new BalanceAndProxyAllowanceLazyStore(
+            this._contractWrappers.token,
+            stateLayer,
+        );
+        this._orderFilledCancelledLazyStore = new OrderFilledCancelledLazyStore(
+            this._contractWrappers.exchange,
+            stateLayer,
+        );
+        this._orderStateUtils = new OrderStateUtils(
+            this._balanceAndProxyAllowanceLazyStore,
+            this._orderFilledCancelledLazyStore,
+        );
+        const orderExpirationCheckingIntervalMsIfExists = _.isUndefined(config)
+            ? undefined
+            : config.orderExpirationCheckingIntervalMs;
+        const expirationMarginIfExistsMs = _.isUndefined(config) ? undefined : config.expirationMarginMs;
+        this._expirationWatcher = new ExpirationWatcher(
+            expirationMarginIfExistsMs,
+            orderExpirationCheckingIntervalMsIfExists,
+        );
+        this._cleanupJobInterval =
+            _.isUndefined(config) || _.isUndefined(config.cleanupJobIntervalMs)
+                ? DEFAULT_CLEANUP_JOB_INTERVAL_MS
+                : config.cleanupJobIntervalMs;
+    }
+    /**
+     * Add an order to the orderWatcher. Before the order is added, it's
+     * signature is verified.
+     * @param   signedOrder     The order you wish to start watching.
+     */
+    public addOrder(signedOrder: SignedOrder): void {
+        assert.doesConformToSchema('signedOrder', signedOrder, schemas.signedOrderSchema);
+        const orderHash = getOrderHashHex(signedOrder);
+        assert.isValidSignature(orderHash, signedOrder.ecSignature, signedOrder.maker);
+        this._orderByOrderHash[orderHash] = signedOrder;
+        this._addToDependentOrderHashes(signedOrder, orderHash);
+        const expirationUnixTimestampMs = signedOrder.expirationUnixTimestampSec.times(1000);
+        this._expirationWatcher.addOrder(orderHash, expirationUnixTimestampMs);
+    }
+    /**
+     * Removes an order from the orderWatcher
+     * @param   orderHash     The orderHash of the order you wish to stop watching.
+     */
+    public removeOrder(orderHash: string): void {
+        assert.doesConformToSchema('orderHash', orderHash, schemas.orderHashSchema);
+        const signedOrder = this._orderByOrderHash[orderHash];
+        if (_.isUndefined(signedOrder)) {
+            return; // noop
+        }
+        delete this._orderByOrderHash[orderHash];
+        delete this._orderStateByOrderHashCache[orderHash];
+        const zrxTokenAddress = this._orderFilledCancelledLazyStore.getZRXTokenAddress();
+
+        this._removeFromDependentOrderHashes(signedOrder.maker, zrxTokenAddress, orderHash);
+        if (zrxTokenAddress !== signedOrder.makerTokenAddress) {
+            this._removeFromDependentOrderHashes(signedOrder.maker, signedOrder.makerTokenAddress, orderHash);
+        }
+
+        this._expirationWatcher.removeOrder(orderHash);
+    }
+    /**
+     * Starts an orderWatcher subscription. The callback will be called every time a watched order's
+     * backing blockchain state has changed. This is a call-to-action for the caller to re-validate the order.
+     * @param   callback            Receives the orderHash of the order that should be re-validated, together
+     *                              with all the order-relevant blockchain state needed to re-validate the order.
+     */
+    public subscribe(callback: OnOrderStateChangeCallback): void {
+        assert.isFunction('callback', callback);
+        if (!_.isUndefined(this._callbackIfExists)) {
+            throw new Error(OrderWatcherError.SubscriptionAlreadyPresent);
+        }
+        this._callbackIfExists = callback;
+        this._eventWatcher.subscribe(this._onEventWatcherCallbackAsync.bind(this));
+        this._expirationWatcher.subscribe(this._onOrderExpired.bind(this));
+        this._cleanupJobIntervalIdIfExists = intervalUtils.setAsyncExcludingInterval(
+            this._cleanupAsync.bind(this),
+            this._cleanupJobInterval,
+            (err: Error) => {
+                this.unsubscribe();
+                callback(err);
+            },
+        );
+    }
+    /**
+     * Ends an orderWatcher subscription.
+     */
+    public unsubscribe(): void {
+        if (_.isUndefined(this._callbackIfExists) || _.isUndefined(this._cleanupJobIntervalIdIfExists)) {
+            throw new Error(OrderWatcherError.SubscriptionNotFound);
+        }
+        this._balanceAndProxyAllowanceLazyStore.deleteAll();
+        this._orderFilledCancelledLazyStore.deleteAll();
+        delete this._callbackIfExists;
+        this._eventWatcher.unsubscribe();
+        this._expirationWatcher.unsubscribe();
+        intervalUtils.clearAsyncExcludingInterval(this._cleanupJobIntervalIdIfExists);
+    }
+    private async _cleanupAsync(): Promise<void> {
+        for (const orderHash of _.keys(this._orderByOrderHash)) {
+            this._cleanupOrderRelatedState(orderHash);
+            await this._emitRevalidateOrdersAsync([orderHash]);
+        }
+    }
+    private _cleanupOrderRelatedState(orderHash: string): void {
+        const signedOrder = this._orderByOrderHash[orderHash];
+
+        this._orderFilledCancelledLazyStore.deleteFilledTakerAmount(orderHash);
+        this._orderFilledCancelledLazyStore.deleteCancelledTakerAmount(orderHash);
+
+        this._balanceAndProxyAllowanceLazyStore.deleteBalance(signedOrder.makerTokenAddress, signedOrder.maker);
+        this._balanceAndProxyAllowanceLazyStore.deleteProxyAllowance(signedOrder.makerTokenAddress, signedOrder.maker);
+        this._balanceAndProxyAllowanceLazyStore.deleteBalance(signedOrder.takerTokenAddress, signedOrder.taker);
+        this._balanceAndProxyAllowanceLazyStore.deleteProxyAllowance(signedOrder.takerTokenAddress, signedOrder.taker);
+
+        const zrxTokenAddress = this._getZRXTokenAddress();
+        if (!signedOrder.makerFee.isZero()) {
+            this._balanceAndProxyAllowanceLazyStore.deleteBalance(zrxTokenAddress, signedOrder.maker);
+            this._balanceAndProxyAllowanceLazyStore.deleteProxyAllowance(zrxTokenAddress, signedOrder.maker);
+        }
+        if (!signedOrder.takerFee.isZero()) {
+            this._balanceAndProxyAllowanceLazyStore.deleteBalance(zrxTokenAddress, signedOrder.taker);
+            this._balanceAndProxyAllowanceLazyStore.deleteProxyAllowance(zrxTokenAddress, signedOrder.taker);
+        }
+    }
+    private _onOrderExpired(orderHash: string): void {
+        const orderState: OrderState = {
+            isValid: false,
+            orderHash,
+            error: ExchangeContractErrs.OrderFillExpired,
+        };
+        if (!_.isUndefined(this._orderByOrderHash[orderHash])) {
+            this.removeOrder(orderHash);
+            if (!_.isUndefined(this._callbackIfExists)) {
+                this._callbackIfExists(null, orderState);
+            }
+        }
+    }
+    private async _onEventWatcherCallbackAsync(err: Error | null, logIfExists?: LogEntryEvent): Promise<void> {
+        if (!_.isNull(err)) {
+            if (!_.isUndefined(this._callbackIfExists)) {
+                this._callbackIfExists(err);
+                this.unsubscribe();
+            }
+            return;
+        }
+        const log = logIfExists as LogEntryEvent; // At this moment we are sure that no error occured and log is defined.
+        const maybeDecodedLog = this._web3Wrapper.abiDecoder.tryToDecodeLogOrNoop<ContractEventArgs>(log);
+        const isLogDecoded = !_.isUndefined(((maybeDecodedLog as any) as LogWithDecodedArgs<ContractEventArgs>).event);
+        if (!isLogDecoded) {
+            return; // noop
+        }
+        const decodedLog = (maybeDecodedLog as any) as LogWithDecodedArgs<ContractEventArgs>;
+        let makerToken: string;
+        let makerAddress: string;
+        switch (decodedLog.event) {
+            case TokenEvents.Approval: {
+                // Invalidate cache
+                const args = decodedLog.args as ApprovalContractEventArgs;
+                this._balanceAndProxyAllowanceLazyStore.deleteProxyAllowance(decodedLog.address, args._owner);
+                // Revalidate orders
+                makerToken = decodedLog.address;
+                makerAddress = args._owner;
+                if (
+                    !_.isUndefined(this._dependentOrderHashes[makerAddress]) &&
+                    !_.isUndefined(this._dependentOrderHashes[makerAddress][makerToken])
+                ) {
+                    const orderHashes = Array.from(this._dependentOrderHashes[makerAddress][makerToken]);
+                    await this._emitRevalidateOrdersAsync(orderHashes);
+                }
+                break;
+            }
+            case TokenEvents.Transfer: {
+                // Invalidate cache
+                const args = decodedLog.args as TransferContractEventArgs;
+                this._balanceAndProxyAllowanceLazyStore.deleteBalance(decodedLog.address, args._from);
+                this._balanceAndProxyAllowanceLazyStore.deleteBalance(decodedLog.address, args._to);
+                // Revalidate orders
+                makerToken = decodedLog.address;
+                makerAddress = args._from;
+                if (
+                    !_.isUndefined(this._dependentOrderHashes[makerAddress]) &&
+                    !_.isUndefined(this._dependentOrderHashes[makerAddress][makerToken])
+                ) {
+                    const orderHashes = Array.from(this._dependentOrderHashes[makerAddress][makerToken]);
+                    await this._emitRevalidateOrdersAsync(orderHashes);
+                }
+                break;
+            }
+            case EtherTokenEvents.Deposit: {
+                // Invalidate cache
+                const args = decodedLog.args as DepositContractEventArgs;
+                this._balanceAndProxyAllowanceLazyStore.deleteBalance(decodedLog.address, args._owner);
+                // Revalidate orders
+                makerToken = decodedLog.address;
+                makerAddress = args._owner;
+                if (
+                    !_.isUndefined(this._dependentOrderHashes[makerAddress]) &&
+                    !_.isUndefined(this._dependentOrderHashes[makerAddress][makerToken])
+                ) {
+                    const orderHashes = Array.from(this._dependentOrderHashes[makerAddress][makerToken]);
+                    await this._emitRevalidateOrdersAsync(orderHashes);
+                }
+                break;
+            }
+            case EtherTokenEvents.Withdrawal: {
+                // Invalidate cache
+                const args = decodedLog.args as WithdrawalContractEventArgs;
+                this._balanceAndProxyAllowanceLazyStore.deleteBalance(decodedLog.address, args._owner);
+                // Revalidate orders
+                makerToken = decodedLog.address;
+                makerAddress = args._owner;
+                if (
+                    !_.isUndefined(this._dependentOrderHashes[makerAddress]) &&
+                    !_.isUndefined(this._dependentOrderHashes[makerAddress][makerToken])
+                ) {
+                    const orderHashes = Array.from(this._dependentOrderHashes[makerAddress][makerToken]);
+                    await this._emitRevalidateOrdersAsync(orderHashes);
+                }
+                break;
+            }
+            case ExchangeEvents.LogFill: {
+                // Invalidate cache
+                const args = decodedLog.args as LogFillContractEventArgs;
+                this._orderFilledCancelledLazyStore.deleteFilledTakerAmount(args.orderHash);
+                // Revalidate orders
+                const orderHash = args.orderHash;
+                const isOrderWatched = !_.isUndefined(this._orderByOrderHash[orderHash]);
+                if (isOrderWatched) {
+                    await this._emitRevalidateOrdersAsync([orderHash]);
+                }
+                break;
+            }
+            case ExchangeEvents.LogCancel: {
+                // Invalidate cache
+                const args = decodedLog.args as LogCancelContractEventArgs;
+                this._orderFilledCancelledLazyStore.deleteCancelledTakerAmount(args.orderHash);
+                // Revalidate orders
+                const orderHash = args.orderHash;
+                const isOrderWatched = !_.isUndefined(this._orderByOrderHash[orderHash]);
+                if (isOrderWatched) {
+                    await this._emitRevalidateOrdersAsync([orderHash]);
+                }
+                break;
+            }
+            case ExchangeEvents.LogError:
+                return; // noop
+
+            default:
+                throw utils.spawnSwitchErr('decodedLog.event', decodedLog.event);
+        }
+    }
+    private async _emitRevalidateOrdersAsync(orderHashes: string[]): Promise<void> {
+        for (const orderHash of orderHashes) {
+            const signedOrder = this._orderByOrderHash[orderHash];
+            // Most of these calls will never reach the network because the data is fetched from stores
+            // and only updated when cache is invalidated
+            const orderState = await this._orderStateUtils.getOrderStateAsync(signedOrder);
+            if (_.isUndefined(this._callbackIfExists)) {
+                break; // Unsubscribe was called
+            }
+            if (_.isEqual(orderState, this._orderStateByOrderHashCache[orderHash])) {
+                // Actual order state didn't change
+                continue;
+            } else {
+                this._orderStateByOrderHashCache[orderHash] = orderState;
+            }
+            this._callbackIfExists(null, orderState);
+        }
+    }
+    private _addToDependentOrderHashes(signedOrder: SignedOrder, orderHash: string): void {
+        if (_.isUndefined(this._dependentOrderHashes[signedOrder.maker])) {
+            this._dependentOrderHashes[signedOrder.maker] = {};
+        }
+        if (_.isUndefined(this._dependentOrderHashes[signedOrder.maker][signedOrder.makerTokenAddress])) {
+            this._dependentOrderHashes[signedOrder.maker][signedOrder.makerTokenAddress] = new Set();
+        }
+        this._dependentOrderHashes[signedOrder.maker][signedOrder.makerTokenAddress].add(orderHash);
+        const zrxTokenAddress = this._getZRXTokenAddress();
+        if (_.isUndefined(this._dependentOrderHashes[signedOrder.maker][zrxTokenAddress])) {
+            this._dependentOrderHashes[signedOrder.maker][zrxTokenAddress] = new Set();
+        }
+        this._dependentOrderHashes[signedOrder.maker][zrxTokenAddress].add(orderHash);
+    }
+    private _removeFromDependentOrderHashes(makerAddress: string, tokenAddress: string, orderHash: string) {
+        this._dependentOrderHashes[makerAddress][tokenAddress].delete(orderHash);
+        if (this._dependentOrderHashes[makerAddress][tokenAddress].size === 0) {
+            delete this._dependentOrderHashes[makerAddress][tokenAddress];
+        }
+        if (_.isEmpty(this._dependentOrderHashes[makerAddress])) {
+            delete this._dependentOrderHashes[makerAddress];
+        }
+    }
+    private _getZRXTokenAddress(): string {
+        const zrxTokenAddress = this._orderFilledCancelledLazyStore.getZRXTokenAddress();
+        return zrxTokenAddress;
+    }
+}
diff --git a/packages/order-watcher/src/types.ts b/packages/order-watcher/src/types.ts
new file mode 100644
index 000000000..57fa20e47
--- /dev/null
+++ b/packages/order-watcher/src/types.ts
@@ -0,0 +1,48 @@
+import { BigNumber } from '@0xproject/utils';
+
+import {
+    BlockParam,
+    BlockParamLiteral,
+    ContractAbi,
+    ContractEventArg,
+    ExchangeContractErrs,
+    FilterObject,
+    LogEntryEvent,
+    LogWithDecodedArgs,
+    Order,
+    OrderState,
+    SignedOrder,
+} from '@0xproject/types';
+
+export enum OrderWatcherError {
+    SubscriptionAlreadyPresent = 'SUBSCRIPTION_ALREADY_PRESENT',
+    SubscriptionNotFound = 'SUBSCRIPTION_NOT_FOUND',
+}
+
+export type EventWatcherCallback = (err: null | Error, log?: LogEntryEvent) => void;
+
+/**
+ * orderExpirationCheckingIntervalMs: How often to check for expired orders. Default=50.
+ * eventPollingIntervalMs: How often to poll the Ethereum node for new events. Default=200.
+ * expirationMarginMs: Amount of time before order expiry that you'd like to be notified
+ * of an orders expiration. Default=0.
+ * cleanupJobIntervalMs: How often to run a cleanup job which revalidates all the orders. Default=1hr.
+ * stateLayer: Optional blockchain state layer OrderWatcher will monitor for new events. Default=latest.
+ */
+export interface OrderWatcherConfig {
+    orderExpirationCheckingIntervalMs?: number;
+    eventPollingIntervalMs?: number;
+    expirationMarginMs?: number;
+    cleanupJobIntervalMs?: number;
+    stateLayer: BlockParamLiteral;
+}
+
+export type OnOrderStateChangeCallback = (err: Error | null, orderState?: OrderState) => void;
+
+export enum InternalOrderWatcherError {
+    NoAbiDecoder = 'NO_ABI_DECODER',
+    ZrxNotInTokenRegistry = 'ZRX_NOT_IN_TOKEN_REGISTRY',
+    WethNotInTokenRegistry = 'WETH_NOT_IN_TOKEN_REGISTRY',
+}
+
+// tslint:disable:max-file-line-count
diff --git a/packages/order-watcher/src/utils/assert.ts b/packages/order-watcher/src/utils/assert.ts
new file mode 100644
index 000000000..f96bcebc1
--- /dev/null
+++ b/packages/order-watcher/src/utils/assert.ts
@@ -0,0 +1,19 @@
+import { assert as sharedAssert } from '@0xproject/assert';
+// We need those two unused imports because they're actually used by sharedAssert which gets injected here
+// tslint:disable-next-line:no-unused-variable
+import { Schema } from '@0xproject/json-schemas';
+// tslint:disable-next-line:no-unused-variable
+import { ECSignature } from '@0xproject/types';
+import { BigNumber } from '@0xproject/utils';
+import { Web3Wrapper } from '@0xproject/web3-wrapper';
+import * as _ from 'lodash';
+
+import { isValidSignature } from '@0xproject/order-utils';
+
+export const assert = {
+    ...sharedAssert,
+    isValidSignature(orderHash: string, ecSignature: ECSignature, signerAddress: string) {
+        const isValid = isValidSignature(orderHash, ecSignature, signerAddress);
+        this.assert(isValid, `Expected order with hash '${orderHash}' to have a valid signature`);
+    },
+};
diff --git a/packages/order-watcher/src/utils/utils.ts b/packages/order-watcher/src/utils/utils.ts
new file mode 100644
index 000000000..af1125632
--- /dev/null
+++ b/packages/order-watcher/src/utils/utils.ts
@@ -0,0 +1,13 @@
+import { BigNumber } from '@0xproject/utils';
+
+export const utils = {
+    spawnSwitchErr(name: string, value: any): Error {
+        return new Error(`Unexpected switch value: ${value} encountered for ${name}`);
+    },
+    getCurrentUnixTimestampSec(): BigNumber {
+        return new BigNumber(Date.now() / 1000).round();
+    },
+    getCurrentUnixTimestampMs(): BigNumber {
+        return new BigNumber(Date.now());
+    },
+};