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Solidity Function/Event Selector Calculator
x402
Solidity Function/Event Selector Calculator is a paid API for AI agents from api.x402node.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).
Computes the 4-byte function selector and full keccak256 topic hash from a Solidity ABI signature string
Price / call$0.01
Success—
StatusUnknown
How this service works
Compute the 4-byte function/error selector and full keccak topic from a solidity signature, e.g. transfer(address,uint256). For decoding tx input prefixes and matching event topics. function selector, 4byte, method id, event topic, keccak signature Accepts payment on Base or Solana — either network works.
Output
Returns the 4-byte hex function selector (first 4 bytes of keccak256 of the signature) and the full 32-byte keccak256 topic hash, suitable for matching transaction input prefixes and EVM event topics
Example use cases
Example prompt
“What's the 4-byte function selector and full keccak256 topic hash for the Solidity signature transfer(address,uint256)?”
Technical details
Endpoint
GEThttps://api.x402node.dev/crypto/selectorWhen to prefer
Use this endpoint when you need to programmatically compute Solidity function selectors or event topic hashes from ABI signatures without running a local Ethereum toolchain or web3 library. Ideal for decoding raw transaction inputs, filtering event logs by topic0, or building ABI-aware transaction parsers on the fly.
Side effects
- Invalid or malformed Solidity signature string returns an error
- Missing signature parameter returns a 400 bad request
- Network timeout or service unavailability returns a 5xx error
- Ambiguous signature with incorrect parameter types may return unexpected selector
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
x402
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