Async Swap
Async Swap is an MEV-capturing DEX: an on-chain order book and matching engine built as a Uniswap v4 hook. Value that searchers usually take from ordering and backruns goes to the protocol and LPs instead. Traders set a limit price for assets paired with USDC. Orders match with other traders or with the pool's active liquidity, and anyone can permissionlessly fill a resting order.
- Price, then bid, then time. Book matching ranks orders by price. Among orders at the same price, a higher escrowed USDC priority bid goes first, and earlier orders break equal bids.
- Ordering MEV is auctioned, not extracted. Priority bids are paid in USDC to the protocol's FeeVault, so jumping the queue at a price costs the bidder, not other traders.
- Backruns pay LPs. Each pool's first fill in a 2-block window records the price before it. A later fill in that window that moves the same pool's price back toward it pays a dynamic fee of about half the backrun's profit, split between LPs and the protocol. Other pools are unaffected. See dynamic fee ordering.
- Orders rest until they execute. Unfilled amounts stay open for later matching, a pool fill, a filler, repricing or cancellation.
- No swap touches the curve directly. Every swap becomes an order. The only AMM swaps are the ones the hook makes to fill a resting order from pool liquidity, and those pay active LPs 0.02% and the protocol 0.01%. Book matches and filler fills take 0.02% of what each side receives.
- Proceeds you can always claim. A book match credits both sides as PoolManager claims, which
you redeem to any address through
TokenClaims(ERC-20) orNativeClaims(ETH), or to your own wallet throughRouter.withdrawClaims. A recipient a token refuses cannot block matching. - Rules the owner cannot change. Anyone can open a USDC pool on the hook. The minimum order, the $0.10 priority-bid cap and the 0.0001-token asset floor are fixed when the hook is deployed; the owner can only collect fees, sweep stranded balances and transfer ownership.
- Batch your actions.
Router.multicallcancels several orders and withdraws claims in one atomic transaction, with no extra approvals.
Where to start
| If you want to | Read |
|---|---|
| Understand the contracts, custody and fees | Protocol overview |
| Follow an order from placement to settlement, and how priority bids are paid | Order lifecycle and priority bids |
| See every call, callback and withdrawal step | Contract call sequences |
| See how backrun MEV is captured for LPs | Dynamic fee ordering |
| Check how prices are compared and rounded | Price keys and crossing |
| Review the audit scope, known issues and previous findings | Audit scope |
| Look up a contract, function or event | Contract reference |
Status
The contracts are on asyncswap/contracts main. Every
finding of the previous reviews is fixed or acknowledged; see the
audit scope. These docs rebuild from that repository on every change to its
sources, guides or audit notes.