{"id":"b5e85378-0d6c-447d-8b20-ed9f24885215","shortId":"b9LUmA","kind":"x402","title":"Query NFT ownership data via x402 micropayment on Base for $0.02 per request.","tagline":"Query NFT ownership data via x402 micropayment on Base for $0.02 per request.","description":"This endpoint at lowpaymentfee.com returns NFT ownership information for NFT #56. It is part of a broader platform offering dozens of pay-per-call API endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all gated behind the x402 payment protocol on the Base network using USDC.\n\nThe specific endpoint `/api/v1/nfts/56/owner` accepts POST requests and returns JSON. Payment is settled on-chain via USDC on Base (contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) with a maximum cost of 20,000 base units, which equals $0.02 (USDC uses 6 decimals). The x402 challenge confirms the endpoint is live and discoverable. No API keys are required; callers simply attach an X-PAYMENT header with a valid x402 payment proof.\n\nThe platform advertises a uniform $0.02-per-request pricing model across all its endpoints, with no rate limits, no minimums, and no commitments. Documentation beyond the landing page is sparse — the /api, /pricing, and /README pages all resolve to a minimal \"Connect wallet\" prompt with no additional technical detail. There is no OpenAPI spec, no request/response schema documentation, and no example payloads available, so the exact request body format and response structure for this NFT owner lookup must be discovered experimentally.","tags":[],"capabilities":["nft-ownership-lookup","x402-payment","usdc-base","pay-per-call","no-api-key","json-response"],"categories":["web3","nft"],"synonyms":["NFT owner lookup","NFT ownership API","who owns NFT","Base USDC micropayment API","x402 NFT endpoint","token holder query"],"warnings":["No OpenAPI or schema documentation available — request body format and response structure are unknown","Site pages (/api, /pricing, /README) return only a 'Connect wallet' prompt with no useful content","This endpoint is scoped to a single NFT (token #56); it is unclear if other token IDs are supported at different paths","No examples or integration guides are provided by the platform"],"endpointUrl":"https://lowpaymentfee.com/api/v1/nfts/56/owner","protocol":"x402","transport":"http","auth":{"type":"x402","details":[{"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","extra":{"name":"USD Coin","version":"2"},"payTo":"0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3","scheme":"exact","network":"base","mimeType":"application/json","resource":"https://lowpaymentfee.com/api/v1/nfts/56/owner","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.350","qualityRationale":"The endpoint is live and returns a valid x402 402 challenge, confirming pricing and payment details. However, there is no OpenAPI spec, no documented request/response schema, no examples, and the broader site pages are empty beyond a wallet-connect prompt. The specific functionality (NFT #56 owner) is narrow and 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'/api/v1/nfts/56/owner':80 '/pricing':177 '/readme':179 '0.02':11,24,110,149 '000':105 '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913':98 '20':104 '56':37 '6':113 'Base USDC micropayment API' 'NFT owner lookup' 'NFT ownership API' 'accept':81 'across':155 'addit':191 'advertis':146 'ai/ml':57 'analyt':56 'api':52,126 'attach':132 'avail':207 'base':9,22,73,96,106 'behind':66 'beyond':169 'bodi':212 'broader':43 'call':51 'caller':130 'chain':92 'challeng':117 'commit':167 'confirm':118 'connect':186 'contract':97 'cost':102 'data':4,17,55,60 'decim':114 'detail':193 'discov':224 'discover':124 'document':168,202 'dozen':46 'endpoint':28,53,79,120,158 'equal':109 'exact':210 'exampl':205 'experiment':225 'finance/web3':59 'format':213 'gate':65 'header':137 'infer':58 'inform':34 'infrastructur':62 'json':86 'json-response' 'key':127 'land':171 'limit':162 'live':122 'lookup':221 'lowpaymentfee.com':30 'maximum':101 'micropay':7,20 'minim':185 'minimum':164 'model':154 'must':222 'network':74 'nft':2,15,32,36,219 'nft-ownership-lookup' 'no-api-key' 'offer':45 'on-chain':90 'openapi':197 'owner':220 'ownership':3,16,33 'page':172,180 'part':40 'pay':49 'pay-per-cal':48 'pay-per-call' 'payload':206 'payment':69,87,136,142 'per':12,25,50,151 'per-request':150 'platform':44,145 'post':82 'price':153 'prompt':188 'proof':143 'protocol':70 'queri':1,14 'rate':161 'request':13,26,83,152,211 'request/response':200 'requir':129 'resolv':182 'respons':215 'return':31,85 'schema':201 'settl':89 'simpli':131 'span':54 'spars':174 'spec':198 'specif':78 'structur':216 'technic':192 'token holder query' 'uniform':148 'unit':107 'usdc':76,94,111 'usdc-base' 'use':75,112 'util':63 'valid':140 'via':5,18,93 'wallet':187 'who owns NFT' 'x':135 'x-payment':134 'x402':6,19,68,116,141 'x402 NFT endpoint' 'x402-payment'","prices":[{"id":"7eeb5e8f-5cd3-42ff-817c-5a2d60698316","listingId":"b5e85378-0d6c-447d-8b20-ed9f24885215","amountUsd":null,"unit":"per_call","nativeCurrency":"USD COIN","nativeAmount":"20000","chain":"base","payTo":"0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3","paymentMethod":"x402-usd coin","isPrimary":true,"details":{"scheme":"exact","mime_type":"application/json","accepts_all":[{"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","extra":{"name":"USD Coin","version":"2"},"payTo":"0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3","scheme":"exact","network":"base","mimeType":"application/json","resource":"https://lowpaymentfee.com/api/v1/nfts/56/owner","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-21T18:32:28.368Z"}],"sources":[{"listingId":"b5e85378-0d6c-447d-8b20-ed9f24885215","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/nfts/56/owner","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:28.368Z","lastSeenAt":"2026-04-22T15:03:11.820Z"}],"details":{"listingId":"b5e85378-0d6c-447d-8b20-ed9f24885215","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/nfts/56/owner \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <x402_payment_proof>\"","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units in USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/nfts/56/owner"},{"claim":"USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","source_url":"https://lowpaymentfee.com/api/v1/nfts/56/owner"},{"claim":"Platform advertises $0.02/request uniform pricing with no API keys, no rate limits, and instant access","source_url":"https://lowpaymentfee.com"},{"claim":"The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories","source_url":"https://lowpaymentfee.com"}],"useCases":["Look up the current owner of a specific NFT (token #56) programmatically","Integrate NFT ownership checks into automated workflows or agents","Demonstrate x402 micropayment protocol usage on Base network"],"bestFor":["Agents needing on-demand NFT ownership data without API key management","Developers experimenting with x402 pay-per-call protocols","Low-volume, ad-hoc NFT owner queries where $0.02/call is acceptable"],"notFor":["Bulk or batch NFT ownership queries across many token IDs (only token #56 is exposed at this path)","Users who need detailed NFT metadata, transaction history, or collection-level data","Applications requiring documented request/response schemas and SLA guarantees"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:12:57.828Z"},"updatedAt":"2026-04-22T15:03:11.820Z"}}