{"uid":"cap_pjEEfJOwN3w6aBcAdGjiD","slug":"evm-calldata-decoder-62cd086a","name":"EVM Calldata Decoder","description":"Decode EVM smart-contract transaction calldata into the function name and typed parameters. Supply an ABI (from /api/contract-abi) or a signature like transfer(address,uint256) for a fully offline decode; with neither, the 4-byte selector is resolved via the openchain.xyz signature database (4byte.directory fallback) and each candidate signature is tried. Unknown selectors return a documented partial decode (selector + raw 32-byte words) instead of an error.","url":"https://agent402.tools/api/calldata-decode","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"abi":{"type":"array","description":"Optional contract ABI (JSON array) - enables a fully offline decode with parameter names."},"data":{"type":"string","description":"0x-prefixed calldata (selector + encoded args). Max 100KB."},"signature":{"type":"string","description":"Optional function signature, e.g. transfer(address,uint256) - offline decode without a full ABI."}}},"responseSchema":{"type":"json","example":{"name":"transfer","params":[{"name":null,"type":"address","value":"0xabf4fabd7c416fb67202e5f9002389fc75e2a9d0"},{"name":null,"type":"uint256","value":"1000000"}],"source":"openchain.xyz","decoded":true,"selector":"0xa9059cbb","signature":"transfer(address,uint256)"}},"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_i5-s-UONbQAWHkF7PKqXf","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":"Decodes EVM smart-contract transaction calldata into a human-readable function name and typed parameters using an ABI, function signature, or 4-byte selector lookup.","exampleAgentPrompt":"Can you decode this calldata for me: 0xa9059cbb000000000000000000000000ab5801a7d398351b8be11c439e05c5b3259aec9000000000000000000000000000000000000000000000000016345785d8a0000 — use the function signature transfer(address,uint256) so we don't need the full ABI.","exampleUseCases":null,"resultDescription":"Returns the decoded function name and a list of typed, named parameters with their values extracted from the calldata, either using the provided ABI, the supplied function signature, or a 4-byte selector resolution from a public registry.","failureModes":["Invalid or malformed calldata hex returns a parse error","Unknown 4-byte selector with no ABI or signature provided results in an unresolvable decode error","Calldata exceeding 100KB is rejected","Mismatched ABI or signature causes parameter decoding to fail with a type mismatch error","Malformed ABI JSON array causes an invalid input error"],"whenToPreferThis":"Use this endpoint when you have raw EVM transaction calldata (0x-prefixed hex) and need to understand what function is being called and with what arguments. Ideal for transaction analysis, debugging contract interactions, building block explorers, or auditing on-chain activity. Prefer this over manual decoding or etherscan lookups when you want a programmatic, offline-capable decode — especially if you already have the ABI or function signature.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T01:07:12.799Z","isFirstParty":false}