{"uid":"cap_U1Pp9YpsDjO2ESyUUuMTa","slug":"fastx402-lab-erc-20-calldata-decoder-85f84b23","name":"FastX402 Lab ERC-20 Calldata Decoder","description":"146 pay-per-call tools for AI agents, from $0.001 per request in USDC on Base or Solana with x402. No account, no API key.","url":"https://fastx402.tools/erc20-calldata-decode?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$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":["data"],"properties":{"data":{"type":"string","description":"Transaction calldata, 0x + hex"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"args":{"type":"object","properties":{"to":{"type":"string"},"amount":{"type":"string"}}},"function":{"type":"string"},"selector":{"type":"string"}}}}}}},"responseSchema":{"type":"json","example":{"args":{"to":"0xfB6916095ca1df60bB79Ce92cE3Ea74c37c5d359","amount":"1500000"},"function":"transfer","selector":"0xa9059cbb"}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.002","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":"$0.002/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_ioCiWe6bVINENVqxS8wK7","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.002","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Decodes ERC-20 transfer, approve, and transferFrom calldata hex into human-readable function name, checksummed addresses, and token amounts","exampleAgentPrompt":"Before I sign this transaction, decode this calldata and tell me exactly what it does — who the recipient is and how many tokens are being transferred: 0xa9059cbb000000000000000000000000fb6916095ca1df60bb79ce92ce3ea74c37c5d3590000000000000000000000000000000000000000000000000000000000016e360","exampleUseCases":[{"title":"Pre-signing transaction safety check","prompt":"I'm about to sign this ERC-20 transaction but I want to verify what it actually does before I approve it — can you decode this calldata for me: 0xa9059cbb000000000000000000000000d8dA6BF26964aF9D7eEd9e03E53415D37aA96045000000000000000000000000000000000000000000000000016345785d8a0000"},{"title":"Verify approve allowance before DeFi interaction","prompt":"My DeFi app is asking me to approve a token spend — can you decode this calldata and tell me which address is getting approved and for exactly how much: 0x095ea7b3000000000000000000000000uniswap_router_address0000000000000000000000000000000000000000000000000de0b6b3a7640000"},{"title":"Audit agent-generated transaction calldata","prompt":"My AI trading agent generated this calldata for a transferFrom call — decode it and tell me the exact sender, recipient, and amount so I can double-check it matches the intended trade: 0x23b872dd000000000000000000000000abc123sender000000000000000000000000def456recipient000000000000000000000000000000000000000000000000002386f26fc10000"}],"resultDescription":"A JSON object containing the decoded ERC-20 function name (e.g. 'transfer', 'approve', 'transferFrom'), the 4-byte function selector (e.g. '0xa9059cbb'), and an args object with checksummed Ethereum addresses (to, from, spender) and the exact token amount as a string integer.","failureModes":["Unrecognized function selector (not transfer/approve/transferFrom) returns an error or null","Malformed or truncated calldata causes a parse error","Missing 0x prefix on input data may cause rejection","Non-ERC-20 calldata (e.g. ETH transfers, other contract calls) will not decode correctly"],"whenToPreferThis":"Use this endpoint when an AI agent or user needs to verify what an ERC-20 transaction calldata actually does before signing or broadcasting it — particularly for safety checks in wallet automation, DeFi interactions, or any agentic workflow that programmatically constructs or receives Ethereum transactions. Prefer this over manual ABI decoding when you need a lightweight, pay-per-call approach without running a full Ethereum node or ABI library.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-17T12:38:49.283Z","isFirstParty":false,"canonicalSlug":"fastx402-lab-erc-20-calldata-decoder-85f84b23"}