Keccak-256 Hash & Function Selector
Hash any string with Keccak-256 and get the 4-byte function selector and 32-byte event topic the EVM uses.
Keccak-256 is the hash function the EVM uses for Solidity's keccak256, function selectors, event topics, and storage slots. This tool hashes a string (or raw hex) and returns the full 32-byte digest plus the first 4 bytes — the function selector that identifies a method like transfer(address,uint256) in calldata.
Keccak-256 is the original Keccak submission that Ethereum adopted (it differs slightly from the finalized NIST SHA-3). It is used pervasively: Solidity's keccak256(), the selectors that route calldata to functions, the topics that index events, and the slot computation for mappings all rely on it. Monad, being EVM-equivalent, uses the same function.
A function selector is the first 4 bytes of the Keccak-256 hash of the function's canonical signature — for example keccak256("transfer(address,uint256)") starts with 0xa9059cbb, the selector that appears at the front of every ERC-20 transfer's calldata. Event topics use the full 32-byte hash of the event signature.
The tool lets you hash either the UTF-8 text of a string or the raw bytes of a 0x hex input, matching how Solidity treats abi.encodePacked of a string versus bytes.
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