Smart contract extensions of 0x protocol

Usage no npm install needed!

<script type="module">
  import 0xContractsExtensions from 'https://cdn.skypack.dev/@0x/contracts-extensions';



This package includes utility smart contracts that may be useful for developing on top of the core 0x Exchange. For example, MixinWethUtils includes functions to pay affiliate fees in ETH, wrap ETH to be used for 0x trades and protocol fees, and unwrap WETH to refund the sender.



npm install @0x/contracts-extensions --save

Bug bounty

A bug bounty for the 3.0 contracts is ongoing! Instructions can be found here.


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) repository and follow the contribution guidelines provided therein.

Please read our contribution guidelines before getting started.

Install Dependencies

If you don't have yarn workspaces enabled (Yarn < v1.0) - enable them:

yarn config set workspaces-experimental true

Then install dependencies

yarn install


To build this package and all other monorepo packages that it depends on, run the following from the monorepo root directory:

PKG=@0x/contracts-extensions yarn build

Or continuously rebuild on change:

PKG=@0x/contracts-extensions yarn watch


yarn clean


yarn lint

Run Tests

yarn test

Testing options

Contracts testing options like coverage, profiling, revert traces or backing node choosing - are described here.