{"uid":"cap_N-cGlrKYd1fKH-uHo6X0J","slug":"saylor-innovations-evm-selector-topic-decoder-98fa2907","name":"Saylor Innovations EVM Selector / Topic Decoder","description":"Decode a 4-byte EVM function selector or 32-byte event topic into candidate signatures from OpenChain and 4byte with the verified one first and collision warnings","url":"https://saylorinnovations.com/api/evm/selector?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":["hex"],"properties":{"hex":{"type":"string","description":"4-byte function selector (0xa9059cbb) or 32-byte event topic"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string","const":"json"},"example":{"type":"object","required":["hex","kind","best_guess"],"properties":{"hex":{"type":"string","description":"The selector or topic that was decoded"},"kind":{"type":"string","description":"Kind of record"},"note":{"type":"string","description":"Caveat or context for reading the result"},"source":{"type":"string","description":"Data source the values come from"},"best_guess":{"type":"string","description":"Best guess"},"candidates":{"type":"array","items":{"type":"object","properties":{"sources":{"description":"Data sources used"},"signature":{"type":["string","null"],"description":"Candidate function or event signature"},"verified_contract_seen":{"description":"Verified contract seen"}}},"description":"Candidate signatures, whether a verified contract using it was seen, and the source databases"},"collision_warning":{"type":["string","null"],"description":"Collision warning"},"well_known_meaning":{"type":["string","null"],"description":"Well known meaning"}}}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.01","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.01/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_dAeeSpK4DYZU8WpZLBMjp","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.01","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Decodes a 4-byte EVM function selector or 32-byte event topic into candidate human-readable signatures, with verification status and collision warnings","exampleAgentPrompt":"What function does the EVM selector 0xa9059cbb correspond to? Give me the best guess signature and let me know if there are any collisions or multiple candidates.","exampleUseCases":[{"title":"Identify unknown contract method call","prompt":"I'm reading a raw Ethereum transaction and the input data starts with 0xa9059cbb — can you decode that 4-byte selector and tell me what function it is?"},{"title":"Debug smart contract event topic","prompt":"I've got this 32-byte event topic from an Ethereum log: 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef — what event does it represent and is it from a verified contract?"},{"title":"Audit ABI collision risk","prompt":"Can you check the EVM selector 0x23b872dd and tell me if there are multiple function signatures that map to it? I need to know if there's a collision warning before I trust it in my security audit."}],"resultDescription":"Returns the input hex selector or topic, its kind (function or event), a best_guess human-readable signature, an array of candidate signatures with their sources (OpenChain and/or 4byte) and whether a verified contract has been seen using each, plus an optional collision_warning if multiple signatures share the selector, and a well_known_meaning field for widely-recognized selectors.","failureModes":["Unknown selector not found in either OpenChain or 4byte databases — returns empty candidates array","Invalid hex format (wrong length or non-hex characters) — request rejected","Selector with multiple conflicting signatures triggers collision warning but still returns results","External database (OpenChain or 4byte) temporarily unavailable — partial or error response","Rate limiting or payment failure for the $0.01 USDC x402 fee"],"whenToPreferThis":"Choose this endpoint when you need to decode an EVM function selector or event topic into its human-readable Solidity signature, especially when you want verification status (confirmed seen in a verified contract) and collision detection. It aggregates both OpenChain and 4byte.directory sources, making it more reliable than querying either alone. Prefer it over manual ABI lookups when building blockchain explorers, transaction analyzers, security auditing tools, or smart contract debugging pipelines.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-18T12:56:23.305Z","isFirstParty":false,"canonicalSlug":"saylor-innovations-evm-selector-topic-decoder-98fa2907"}