{"uid":"cap_WSsa3sycUgTKHRAAu4_Te","slug":"delx-commerce-evm-transaction-selector-extractor-73a3c068","name":"Delx Commerce — EVM Transaction Selector Extractor","description":"Pay-per-result APIs for agents. No signup. Exact price. Verifiable delivery. USDC on Base + Solana via x402.","url":"https://commerce.delx.ai/api/v1/x402/selector-extract?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"calldata":{"type":"string","description":"Transaction calldata hex; first 4 bytes are the selector."}}},"responseSchema":{"type":"json","example":{"valid":true,"schema":"delx/util-selector-extract/v1","selector":"0xa9059cbb","remaining_bytes":32}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.003","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":"$0.003/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.003","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.003","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_oUh-Lb-DKbjq9PW0AqDkH","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.003","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Extracts the 4-byte ABI function selector and remaining calldata byte count from raw EVM transaction calldata hex.","exampleAgentPrompt":"Can you extract the function selector from this EVM transaction calldata: 0xa9059cbb000000000000000000000000ab5801a7d398351b8be11c439e05c5b3259aec9000000000000000000000000000000000000000000000000000000003b9aca00 — I want to know which function it's calling and how many bytes of parameters follow.","exampleUseCases":[{"title":"Identify ERC-20 transfer calls","prompt":"I have this raw calldata from an Ethereum transaction: 0xa9059cbb0000000000000000000000001234567890abcdef1234567890abcdef123456780000000000000000000000000000000000000000000000000de0b6b3a7640000 — can you extract the function selector and tell me how many parameter bytes are in it?"},{"title":"Audit unknown smart contract invocation","prompt":"Someone sent a suspicious transaction to a smart contract and I have the raw calldata hex: 0x23b872dd000000000000000000000000abc — what function selector is being called and how many bytes of arguments does it carry?"},{"title":"Decode calldata in blockchain agent pipeline","prompt":"As part of my transaction monitoring pipeline, decode the function selector from this calldata hex 0x095ea7b3000000000000000000000000router00000000000000000000000000000000ffff and confirm whether it's a valid ABI-encoded call."}],"resultDescription":"Returns a JSON object with a validity boolean, a schema identifier string (e.g. 'delx/util-selector-extract/v1'), the extracted 4-byte function selector as a hex string (e.g. '0xa9059cbb'), and the count of remaining bytes after the selector in the calldata.","failureModes":["Malformed or non-hex calldata string returns valid:false","Calldata shorter than 4 bytes cannot yield a selector","Missing 'calldata' field in request body causes validation error","Payment failure via x402 protocol prevents execution","Truncated calldata may return a selector but incorrect remaining_bytes count"],"whenToPreferThis":"Use this endpoint when you need a lightweight, pay-per-use, no-signup way to programmatically extract and validate the ABI function selector from raw EVM transaction calldata. It is ideal for blockchain agents, transaction monitoring pipelines, and smart contract auditing tools that need to quickly identify which Solidity function a raw hex payload targets without spinning up a local EVM decoder. Prefer it over full node RPC calls or heavy decoding libraries when you only need the selector and byte count in a single fast API call.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-02T02:28:16.380Z","isFirstParty":false,"canonicalSlug":"delx-commerce-evm-transaction-selector-extractor-73a3c068"}