3 services carry this tag in their source record. Tags come from the provider, not from us — a tag is a claim about what the service does, not proof that it does it well.
Keccak hash, keccak256. Keccak-256 hash (the Ethereum hash) of text or of 0x hex bytes, as used for function selectors, event topics and storage slots. Use when building or decoding EVM calls.
EVM developer utilities toolbox. One call that works out what an EVM value is and converts it every useful way: an address gets its EIP-55 checksum and bytes32 form; a signature its 4-byte selector and event topic; calld...
Turns a Solidity signature like transfer(address,uint256) into its 4-byte function selector and its 32-byte event topic0. What you need to build calldata by hand or to filter logs.