UniswapX

UniswapX is an ERC20 swap settlement protocol that provides swappers with a gasless experience, MEV protection, and access to arbitrary liquidity sources. Swappers generate signed orders which specify the specification of their swap, and fillers compete using arbitrary fill strategies to satisfy these orders.

UniswapX Protocol Architecture

Reactors

Order Reactors settle UniswapX orders. They are responsible for validating orders of a specific type, resolving them into inputs and outputs, and executing them against the filler's strategy, and verifying that the order was successfully fulfilled.

Reactors process orders using the following steps:

• Validate the order
• Resolve the order into inputs and outputs
• Pull input tokens from the swapper to the fillContract using permit2 permitWitnessTransferFrom with the order as witness
• Call reactorCallback on the fillContract
• Verify that the output tokens were received by the output recipients

Reactors implement the IReactor interface which abstracts the specifics of the order specification. This allows for different reactor implementations with different order formats to be used with the same interface, allowing for shared infrastructure and easy extension by fillers.

Current reactor implementations:

• LimitOrderReactor: A reactor that settles simple static limit orders
• DutchOrderReactor: A reactor that settles linear-decay dutch orders
• ExclusiveDutchOrderReactor: A reactor that settles linear-decay dutch orders with a period of exclusivity before decay begins

Fill Contracts

Order fillContracts fill UniswapX orders. They specify the filler's strategy for fulfilling orders and are called by the reactor with reactorCallback.

Some sample fillContract implementations are provided in this repository:

• SwapRouter02Executor: A fillContract that uses UniswapV2 and UniswapV3 via the SwapRouter02 router

Direct Fill

If a filler wants to fill orders using funds on-hand rather than a fillContract, they can do so gas efficiently using the directFill macro by specifying address(1) as the fillContract. This will pull tokens from the filler using msg.sender to satisfy the order outputs.

Integrating with UniswapX

Jump to the docs for Creating a Filler Integration.

Deployment Addresses

Usage

# install dependencies
forge install

# compile contracts
forge build

# run unit tests
forge test

# run integration tests
FOUNDRY_PROFILE=integration forge test

Audit

This codebase was audited by ABDK.

Bug Bounty

This repository is subject to the Uniswap Labs Bug Bounty program, per the terms defined here.