{"uid":"cap_fRAU5jt8_JvFGbwLdyY_A","slug":"solidity-function-selector-calculator-10f9ce55","name":"Solidity Function Selector Calculator","description":"Function selector from a Solidity signature — Genesis402 / UnyKorn Operator Network","url":"https://twin.unykorn.org/abi-function-selector?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"params":{"type":"object","properties":{"signature":{"type":"string"}}}}},"responseSchema":{"type":"json","example":{"ok":true,"type":"abi-function-selector","receipt":{"tx_hash":"0x<64hex>","amount_usd":0.001,"receipt_id":"g402-<16hex>"},"generated_at":"<iso8601>"}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.001","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":"$0.001/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_QWPGB5OkqJzvq5i9amAaP","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.001","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes the 4-byte ABI function selector from a Solidity function signature string","exampleAgentPrompt":"What's the ABI function selector for the Solidity signature transfer(address,uint256)? I need the 4-byte hex value.","exampleUseCases":[{"title":"Debugging raw EVM calldata","prompt":"I'm looking at some raw transaction calldata and need to figure out which function was called — can you give me the selector for balanceOf(address) so I can compare it to the first 4 bytes?"},{"title":"Building a smart contract interaction tool","prompt":"I'm writing a script to manually encode a function call to approve(address,uint256) — what's the 4-byte function selector I need to prepend to the ABI-encoded arguments?"},{"title":"Verifying selector collision between functions","prompt":"I want to check the function selectors for transferFrom(address,address,uint256) and any potential collisions — can you compute the selector for that signature?"}],"resultDescription":"Returns a JSON object confirming success, the computed 4-byte ABI function selector hex string derived from the provided Solidity signature, along with a payment receipt including transaction hash, amount in USD, and a unique receipt ID.","failureModes":["Invalid or malformed Solidity signature string causes an error response","Missing required 'signature' field in the params object","Network timeout or service unavailability returns a non-200 response","Payment failure via x402 protocol prevents computation","Signature with unsupported or non-standard types may produce unexpected results"],"whenToPreferThis":"Choose this endpoint when you need a quick, paid, on-demand computation of the Solidity ABI function selector from a human-readable function signature, especially in agentic workflows that already use the x402 micropayment protocol. Prefer it when you want a verifiable receipt of the computation and are working within the UnyKorn/Genesis402 ecosystem alongside other blockchain utilities like calldata splitting or EVM chain lookups.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-01T18:55:33.865Z","isFirstParty":false,"canonicalSlug":"solidity-function-selector-calculator-10f9ce55"}