{"uid":"cap_M-fcpFlRadEJqJkIa9ETk","slug":"calldata-decoder-887c02b3","name":"Calldata Decoder","description":"Decode EVM transaction input data: looks up the 4-byte function selector and decodes every argument (addresses, amounts, arrays). Use to see what a transaction or signing request will really do.","url":"https://bess-x402.onrender.com/v1/evm/decode-calldata?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","HEAD","DELETE"],"type":"string"},"queryParams":{"type":"object","required":["data"],"properties":{"data":{"type":"string","description":"0x calldata"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":null,"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_OMp_G_-ihdNOJzZwtzMVs","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 raw EVM transaction calldata by resolving the 4-byte function selector and unpacking all arguments into human-readable form.","exampleAgentPrompt":"Can you decode this EVM calldata and tell me what function it calls and what all the arguments are: 0xa9059cbb000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa960450000000000000000000000000000000000000000000000056bc75e2d63100000","exampleUseCases":[{"title":"Verify a DeFi signing request","prompt":"Before I sign this transaction, can you decode the calldata 0x23b872dd000000000000000000000000abc...def000000000000000000000000xyz...123000000000000000000000000000000000000000000000000002386f26fc10000 and tell me exactly what function it's calling and what the arguments are?"},{"title":"Audit an on-chain transaction","prompt":"I found this suspicious transaction on Ethereum with input data 0x38ed1739000000000000000000000000... — can you decode the calldata and show me the function name and every argument so I can understand what it actually did?"},{"title":"Debug a smart contract interaction","prompt":"My smart contract call failed — can you decode this calldata 0x7ff36ab5000000000000000000000000... so I can see what function was called and whether the addresses and amounts were passed in correctly?"}],"resultDescription":"Returns the resolved function name and signature derived from the 4-byte selector, plus each decoded argument with its type and value — including addresses (checksummed), token amounts, booleans, arrays, and nested tuples — giving a complete human-readable breakdown of what the transaction will execute.","failureModes":["Unknown 4-byte selector not in lookup database — function name cannot be resolved","Malformed or truncated calldata — ABI decoding fails with a parse error","Non-hex or missing 0x prefix in input — returns validation error","Empty calldata (e.g. plain ETH transfer with no input) — no function to decode","ABI ambiguity when multiple functions share the same 4-byte selector"],"whenToPreferThis":"Use this endpoint when you need to understand what an EVM transaction or signing request will actually do before approving or broadcasting it, or when auditing historical on-chain transactions. It is specifically suited for decoding raw hex calldata without needing to supply your own ABI — the endpoint performs the selector lookup automatically. Prefer this over manual ABI decoding tools when working in an automated agent pipeline that needs structured argument output.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-30T07:12:25.733Z","isFirstParty":false,"canonicalSlug":"calldata-decoder-887c02b3"}