Keccak-256 & Solidity Signature Calculator
Calculate Ethereum Keccak-256 hashes, Solidity function selectors, and event topic0 hashes from text, hex, or signatures.
25 input bytes · Hash the canonical signature exactly as entered
Keccak-256 hash
0xa9059cbb2ab09eb219583f4a59a5d0623ade346d962bcd4e46b11da047c9049b
Function selector (first 4 bytes)
0xa9059cbb
Event topic0 (full 32 bytes)
0xa9059cbb2ab09eb219583f4a59a5d0623ade346d962bcd4e46b11da047c9049b
Use the selector for contract function calldata. Use the full topic0 hash to filter non-anonymous Solidity events.
More
Related tools
ETH Unit Converter
Convert Wei, Gwei, and Ether with exact precision, then estimate Ethereum gas fees. Free ETH unit calculator — no rounding errors or sign-up.
Ethereum Address Checksum
Validate an Ethereum address and convert it to the EIP-55 checksummed format. Free, private, and entirely browser-based.
JSON Formatter
Format, validate, and minify JSON online for free. Instantly catch syntax errors, apply clean indentation, and minify with one click — no sign-up needed.
Base64 Encoder / Decoder
Encode or decode Base64 text and files instantly online. Free Base64 converter for JWTs, data URLs, and auth headers — everything runs in your browser.
Frequently asked questions
What is Keccak-256 & Solidity Signature Calculator?+
Calculate Ethereum's Keccak-256 hash from UTF-8 text or hexadecimal bytes, or enter a canonical Solidity signature.
How do I use Keccak-256 & Solidity Signature Calculator?+
Shows the complete 32-byte Keccak-256 hash. Extracts the first 4 bytes as a Solidity function selector. Provides the full hash as event topic0 for log filtering. Keccak-256 is different from standardized SHA3-256; all calculations run locally
Is Keccak-256 & Solidity Signature Calculator free?+
Yes, Keccak-256 & Solidity Signature Calculator is completely free. No account or sign-up required, and all processing happens in your browser — nothing is sent to a server.
Is my data safe when I use Keccak-256 & Solidity Signature Calculator?+
Yes. Keccak-256 & Solidity Signature Calculator runs entirely in your browser using JavaScript and Web APIs — your input is never uploaded, transmitted, or stored on any server.