{"uid":"cap_4u-QTE6PzTdg3qBej7Pci","slug":"agent402-erc-721-owner-lookup-d7b602b1","name":"Agent402 ERC-721 Owner Lookup","description":"Who owns this NFT? Calls ownerOf(tokenId) on any ERC-721 contract on Ethereum, Base, Polygon, Arbitrum, or Optimism. Complements nft-holdings (which lists a WALLET's NFTs) - this answers by TOKEN. Keyless multi-endpoint failover. ?contract=0x…&tokenId=123&network=ethereum","url":"https://agent402.tools/api/erc721-owner","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":["contract","tokenId"],"properties":{"network":{"type":"string","description":"ethereum / base / polygon / arbitrum / optimism (default base)."},"tokenId":{"type":"string","description":"Token id - decimal or 0x hex string."},"contract":{"type":"string","description":"ERC-721 contract address (0x…)."}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","required":["network","contract","tokenId","owner"],"properties":{"owner":{"type":"string"},"network":{"type":"string"},"tokenId":{"type":"string"},"contract":{"type":"string"}}}}}}},"responseSchema":{"type":"json","example":{"owner":"0x…","network":"ethereum","tokenId":"0xaf2c…","contract":"0x57f1…"}},"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_gdhf3feBDnPvDzRZzH2mN","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":"Returns the current owner address of a specific ERC-721 NFT token given a contract address and token ID, across multiple EVM-compatible networks.","exampleAgentPrompt":"Who currently owns token ID 5765 of the ERC-721 contract 0x57f1887a8BF19b14fC0dF6Fd9B2acc9Af147eA85 on Ethereum?","exampleUseCases":[{"title":"NFT provenance verification","prompt":"Can you check who currently owns token ID 1234 of the NFT contract 0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D on Ethereum? I need to verify the current holder before making an offer."},{"title":"Cross-chain NFT ownership audit","prompt":"Find out who holds token 42 of contract 0x8a90CAb2b38dba80c64b7734e58Ee1dB38B8992e on Base — I'm building a dashboard that tracks ownership across chains."},{"title":"NFT gating access check","prompt":"Look up the owner of token ID 0xaf2c on the ERC-721 contract 0x57f1887a8BF19b14fC0dF6Fd9B2acc9Af147eA85 on Polygon so I can verify if a user is eligible for gated content."}],"resultDescription":"Returns a JSON object containing the owner wallet address (0x…), the blockchain network queried, the token ID (normalized), and the contract address. This allows the agent to definitively identify the current on-chain holder of a specific NFT.","failureModes":["Invalid contract address (not a valid ERC-721 contract) returns an error","Token ID does not exist on the specified contract","Unsupported network name returns an error","Contract address is not checksummed or malformed","Network RPC unavailable causing a timeout"],"whenToPreferThis":"Use this endpoint when you need a lightweight, pay-per-call NFT owner lookup without signing up for an API key or managing an RPC provider. It covers multiple EVM networks (Ethereum, Base, Polygon, Arbitrum, Optimism) in a single interface and is ideal for agents that need on-demand ownership verification as part of a larger workflow, especially within an x402 payment-enabled pipeline.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T19:14:05.145Z","isFirstParty":false}