{"slug":"agent402-tools-api-selector-lookup-3e1042","title":"Resolve a 4-byte function selector or a 32-byte event topic hash to its known hu","host":"agent402.tools","method":"POST","resource":"https://agent402.tools/api/selector-lookup","category":"other","description":"Resolve a 4-byte function selector or a 32-byte event topic hash to its known human-readable Solidity signatures, via the openchain.xyz signature database with 4byte.directory as fallback. Unknown selectors return {found:false} with an empty list, not an error.","price_listed":0.002,"price_asked":0.002,"state":"answering","state_label":"Answering","checks_7d":1,"answered_7d":1,"latency_ms_median":944,"reported_calls_30d":7,"reported_payers_30d":1,"networks":["algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8=","eip155:10","eip155:1329","eip155:137","eip155:143","eip155:42161","eip155:42220","eip155:43114","eip155:4663","eip155:8453","solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp","stellar:pubnet"],"badge":"unverified","paid_checks_7d":0,"paid_ok_7d":0,"example_input":{"body":{"selector":"0xa9059cbb"},"bodyType":"json","method":"POST","type":"http"},"output_schema":{"$schema":"https://json-schema.org/draft/2020-12/schema","properties":{"input":{"additionalProperties":false,"properties":{"body":{"properties":{"selector":{"description":"0x-prefixed 4-byte function selector (10 chars) or 32-byte event topic hash (66 chars).","type":"string"}},"required":["selector"]},"bodyType":{"enum":["json","form-data","text"],"type":"string"},"method":{"enum":["POST"],"type":"string"},"type":{"const":"http","type":"string"}},"required":["type","method","bodyType","body"],"type":"object"},"output":{"properties":{"example":{"properties":{"found":{"type":"boolean"},"kind":{"type":"string"},"selector":{"type":"string"},"signatures":{"items":{"type":"string"},"type":"array"},"source":{"type":"string"}},"required":["selector","kind","found","signatures","source"],"type":"object"},"type":{"type":"string"}},"required":["type"],"type":"object"}},"required":["input"],"type":"object"},"history":[{"day":"2026-09-24","reachable":true,"status":402,"valid_402":true,"asked_usdc":0.002,"price_match":true,"latency_ms":944,"error":null}],"description_full":"Resolve a 4-byte function selector or a 32-byte event topic hash to its known human-readable Solidity signatures, via the openchain.xyz signature database with 4byte.directory as fallback. Unknown selectors return {found:false} with an empty list, not an error.","last_updated":"2026-09-22T11:55:36.926Z","schemes":["exact","upto"]}