Function Signature Database
Smart Contract Function Lookup
Search function signatures using 4byte.directory. Lookup selectors, search by function name, or calculate selectors from signatures. Essential for analyzing unknown contracts.
Selector Input
What is 4byte.directory?
4byte.directory is a public database of Ethereum function signatures. It helps identify unknown function calls by mapping 4-byte selectors to their human-readable signatures. Essential for analyzing contracts without source code.
Function Selectors
Function selectors are the first 4 bytes of the Keccak256 hash of a function signature. They're used by the EVM to route function calls. Example: transfer(address,uint256) → 0xa9059cbb
Use Cases
Decode transaction data, identify malicious functions, reverse engineer contracts, verify function calls, and understand contract interactions during security audits.