HOOK INSPECTOR
Paste a Uniswap v4 hook address — read exactly which callbacks it's allowed to run. A hook's powers are written into its address, so they decode instantly; then it auto-checks on-chain whether a real contract is actually deployed there.
Open the live analyzerThe story
After building a v4 hooks kit, the question I kept hearing was the simplest one: “okay… but what does this hook actually do?” A hook can quietly sit on every swap, every liquidity move, every fee — and from the outside it's just an address.
Except in v4 it isn't just an address. Uniswap encodes a hook's enabled callbacks into the low 14 bits of where it's deployed — that's why hooks are mined to specific addresses. So the answer is sitting right there, no chain query required.
Hook Inspector reads those bits and tells you, in plain English, every point a hook can intervene — before you trade against it.
One catch I had to get right: every address decodes to some permission set, because that's just the encoding — it doesn't prove a hook is actually there. So the tool also checks on-chain whether a contract is really deployed at that address, across chains, and says so plainly. Permissions first, reality second.
What it does
- Input
- Any Uniswap v4 hook address — nothing else.
- Permissions
- The exact set of callbacks a hook there is allowed to run, in plain English, grouped by lifecycle stage.
- Local decode
- Permissions are baked into the low 14 bits of the address, so they're read instantly in the browser — no ABI, no node.
- Deployment check
- Auto-verifies on-chain whether a contract actually exists at the address (Ethereum, Unichain, Base, Arbitrum, Optimism, Polygon) — so you never mistake an address's encoding for a real hook.
- Bit map
- A live view of the 14 permission bits and the flags hex, so you see the encoding itself.
- Presets
- One-click example addresses — dynamic fee, fee-skim, TWAP oracle, all-hooks, plain pool.
Under the hood
Companion to HOOKED, the v4 hooks kit — the kit builds hooks, the inspector reads them.