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x402 Bazaar — EVM Function Selector Decoder
x402
x402 Bazaar — EVM Function Selector Decoder is a paid API for AI agents from api.relai.fi, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).
Resolves a 4-byte Ethereum function selector or calldata to human-readable ABI signatures via 4byte.directory, paid with micro-USDC via x402 protocol
Price / call$0.01
Success—
StatusUnknown
How this service works
Resolves a 4-byte function selector (e.g. 0x70a08231) to candidate human-readable signatures via 4byte.directory. Accepts a bare selector or full calldata. Paid via x402: $0.005 in USDC on Base (eip155:8453) to 0x973a31858f4d2125f48c880542da11a2796f12d6. Returns 402 with payment requirements; pay and retry.
Output
Returns one or more candidate human-readable function signatures (e.g. 'transfer(address,uint256)') that match the provided 4-byte selector, sourced from the 4byte.directory database.
Example use cases
Example prompt
“Can you decode the Ethereum function selector 0xa9059cbb and tell me what human-readable Solidity function signature it maps to?”
Technical details
Endpoint
POSThttps://api.relai.fi/relay/1782567677091/api/x402/decode-selectorWhen to prefer
Use this endpoint when you need to decode an unknown EVM function selector (4-byte hex) back to a human-readable Solidity signature — especially useful when analyzing smart contract calldata, debugging transactions, or building EVM tooling. Prefer this over querying 4byte.directory directly when you want a pay-per-call micropayment model via x402 without API key management.
Side effects
- Unknown selector not present in 4byte.directory returns empty results
- Malformed or non-hex selector returns a 400-style validation error
- Payment not included or insufficient triggers 402 response with USDC payment requirements on Base
- Selector provided with invalid length (not 4 bytes) rejected
- Network issues reaching 4byte.directory upstream cause 502/timeout
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
x402
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