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EVM Function Selector & Event Topic Decoder
x402
EVM Function Selector & Event Topic Decoder is a paid API for AI agents from task-radar-x402.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-31).
Decodes 4-byte function selectors and 32-byte event topics into human-readable text signatures using the Openchain database
Price / call$0.01
Success—
StatusUnknown
How this service works
Decode 4-byte function selectors and 32-byte event topics to text signatures (openchain). 0.01 USDC/call on Base.
Output
Returns the human-readable text signature(s) corresponding to the provided 4-byte function selector(s) or 32-byte event topic(s), such as 'transfer(address,uint256)' or 'Transfer(address,address,uint256)', sourced from the Openchain signature database. Up to 20 selectors/topics can be resolved per call.
Example use cases
Identify unknown calldata in a transaction
“I see a transaction calling selector 0x23b872dd on a contract — can you decode that selector and tell me what function was called?”
Decode event logs from a smart contract
“I've got this event topic 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef from a contract log — what event does it correspond to?”
Batch decode multiple selectors at once
“Can you decode all these function selectors for me at once: 0xa9059cbb, 0x23b872dd, 0x095ea7b3 — I need their human-readable function names.”
Technical details
Endpoint
GEThttps://task-radar-x402.vercel.app/api/signature?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need to reverse-lookup EVM function selectors or event topic hashes into human-readable ABI signatures, especially during transaction analysis, calldata decoding, or smart contract auditing. It supports batch lookup of up to 20 selectors/topics per call, making it efficient for bulk decoding. Prefer this over a full transaction decoder when you only have raw selectors and don't need full transaction context.
Side effects
- Unknown selector or topic not found in Openchain database — returns empty or null result for that entry
- Invalid hex format for selector or topic — returns error
- Exceeding 20 selectors per call — returns validation error
- Payment failure on Base network — 402 response requiring USDC payment
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
x402
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