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Keccak256 Hash & Ethereum Function Selector Calculator
x402
Keccak256 Hash & Ethereum Function Selector Calculator is a paid API for AI agents from api.x402node.dev, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-14).
Computes the exact keccak256 hash and 4-byte function selector for any string or hex input, as used in Ethereum/Solidity smart contracts
Price / call$0.004
Success—
StatusUnknown
How this service works
Compute the exact keccak256 hash and 4-byte function selector of any string or hex input - the precise Ethereum hash that LLMs cannot calculate correctly. keccak256, keccak hash, function selector, solidity hash, ethereum hash, 4byte selector
Output
Returns the full keccak256 hash (32 bytes, hex-encoded) and the first 4 bytes as the Ethereum ABI function selector for the given input string or hex data
Example use cases
Example prompt
“What's the exact keccak256 hash and 4-byte function selector for the Solidity function signature 'transfer(address,uint256)'?”
Technical details
Endpoint
POSThttps://api.x402node.dev/crypto/keccakWhen to prefer
Use this endpoint when you need a provably correct keccak256 hash or Ethereum function selector — LLMs cannot compute keccak256 accurately from first principles, so any time a smart contract interaction, ABI encoding, event topic, or Solidity hash is needed, this API provides the correct cryptographic result
Side effects
- Invalid or malformed input returns an error response
- Empty input may return a hash of empty string (edge case to handle carefully)
- Non-hex input passed as hex may cause parsing errors
- Network or payment authorization failure returns 402 or 5xx
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| data | string | Data (optional) |
| text | string | String or 0x-hex to hash (required, max 100KB) |
| input | string | Input (optional) |
Tags
x402
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