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Solidity Function Selector

Compute the 4‑byte function selector (keccak‑256) for any Solidity function signature.

Runs in your browser
No upload on server
Free, forever

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Function signature

Use canonical types — no parameter names, no spaces. Example: transfer(address,uint256).

4‑byte selector

0xa9059cbb

Common examples

The selector is the first 4 bytes of keccak256("transfer(address,uint256)"). EVM contracts use it to route calls.

How this works — and why it's private

Type a Solidity function signature. We hash it with keccak‑256 in your browser and show the 4‑byte selector you'd use in data for an EVM transaction.

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