What are custom Uniswap v4 hooks?

If you've seen the Custom Uniswap v4 Hook Request option in our liquidity integration forms and weren't sure what it refers to, this article gives a quick conceptual overview. Hooks are a Uniswap protocol feature, not a 0x one, so for authoritative detail see Uniswap's own documentation: the What is a hook on Uniswap v4? support article and the Hooks concept page in the Uniswap developer docs.

The basic idea

Hooks are smart contract plugins that can customize how pools, swaps, fees, and liquidity positions operate. Like extensions can add tools to your web browser, hooks can add more functionality to liquidity pools and positions on the Uniswap v4 protocol. They're a new feature introduced in Uniswap v4.

The core concept is lifecycle points. Hooks enable developers and liquidity providers to execute actions at specific stages of a pool's lifecycle — such as before or after a swap, or when liquidity is added or removed — allowing for greater customization of liquidity pools and positions. A hook is attached when a pool is created, and while every pool can have one hook, a single hook can serve an unlimited number of pools.

What hooks are used for

Uniswap gives these examples of what hooks make possible: a time-weighted average market maker (TWAMM), dynamic fees based on volatility or other inputs, and on-chain limit orders. The developer docs add further potential, including customized AMMs with pricing curves other than xy = k, yield farming and liquidity mining protocols, derivative and synthetic asset platforms, and lending hooks integrated with v4 pools.

Why this matters in the 0x ecosystem

0x aggregates liquidity across many sources. A custom v4 hook can represent a distinct pool of liquidity with its own behavior, so if you've built one and want trades routed to it through 0x, you can request integration — that's the purpose of the Custom Uniswap v4 Hook path in our liquidity forms.

This connects to a point Uniswap makes directly: building a hook does not by itself mean liquidity will be routed to it from the Uniswap frontend. The same is true for 0x — routing isn't automatic, which is why integration requests are reviewed by the 0x engineering team.

A note on caution

Uniswap is explicit about risk: hooks are developed by independent third-party developers who are not affiliated with Uniswap Labs, and some may be malicious or cause unintended consequences, so caution should be exercised when adding them. A hook's behavior is defined entirely by whoever built it.

How to apply

If you've built a custom Uniswap v4 hook and want it integrated into the 0x ecosystem, submit the Custom Uniswap v4 Hook Request. For how submissions are handled, see our article on applying as a liquidity source in the 0x ecosystem.