{"uid":"cap_YApFy_9QlB0QWwsh0pDif","slug":"base-erc-721-owner-lookup-ee5fadb5","name":"Base ERC-721 Owner Lookup","description":"ARYSPHERE sells AI-written verdicts on Base token contracts (a grade, a one-liner, a roast and the contract's facts) and Base/Ethereum chain reads, paid per call in USDC on Base over x402 v2. No account and no API key.","url":"https://api.arysphere.com/v1/ventures/x402_chain_reads_v1/base_erc721_ownerof?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET","HEAD","DELETE"],"type":"string"},"queryParams":{"type":"object","properties":{"id":{"type":"string","description":"token id, decimal"},"token":{"type":"string","pattern":"^0x[0-9a-fA-F]{40}$","description":"ERC-721 contract, 0x + 40 hex"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":{"type":"json","example":{"ok":true,"chain":"base","method":"ownerOf","result":{"id":"5256424","owner":"0x456979e89917f4dc1e86662fcdfd4c9766c6684d","token":"0xa990c6a764b73bf43cee5bb40339c3322fb9d55f"},"service":"x402_chain_reads_v1.base_erc721_ownerof"}},"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_ROrILPhfdEnb8ZL_8UuF-","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":"Returns the current owner address of a specific NFT token ID on the Base blockchain by calling ownerOf() on the ERC-721 contract.","exampleAgentPrompt":"Who currently owns token ID 5256424 on the Base NFT contract 0xa990c6a764b73bf43cee5bb40339c3322fb9d55f?","exampleUseCases":[{"title":"Verify NFT ownership before transfer","prompt":"Before I send that NFT, can you confirm who currently owns token ID 101 on the Base contract 0xa990c6a764b73bf43cee5bb40339c3322fb9d55f? I want to make sure it's still in my wallet."},{"title":"Gate content by NFT ownership","prompt":"Check who owns token ID 7 on Base NFT contract 0xa990c6a764b73bf43cee5bb40339c3322fb9d55f — I need to verify the holder's address before granting them access to the private channel."},{"title":"Track NFT after marketplace sale","prompt":"I think token ID 888 on Base contract 0xa990c6a764b73bf43cee5bb40339c3322fb9d55f just sold — can you look up who the new owner is right now?"}],"resultDescription":"A JSON object containing: ok (boolean success flag), chain ('base'), method ('ownerOf'), and a result object with the token's id, the owner wallet address, and the contract token address. Returns the exact on-chain ownerOf() response for the given token ID.","failureModes":["Invalid contract address format (not 0x + 40 hex) returns a 400-level error","Token ID that does not exist on the contract may return a revert or null owner","Contract address is not an ERC-721 contract — call will fail or return unexpected data","Network issues reaching Base RPC may cause timeout or 5xx error","Token ID provided as non-decimal string may fail validation"],"whenToPreferThis":"Choose this endpoint when you need to resolve the current on-chain owner of a specific ERC-721 NFT on the Base L2 network. Prefer this over Ethereum ERC-721 lookups when the NFT collection is deployed on Base (not Ethereum mainnet). Useful for ownership verification, access gating, post-sale tracking, or any workflow where knowing the current holder wallet address is required.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-17T12:40:58.655Z","isFirstParty":false,"canonicalSlug":"base-erc-721-owner-lookup-ee5fadb5"}