{"id":"12b79bab-a192-4544-873c-64ccdd51e7a6","shortId":"s2crhH","kind":"x402","title":"x402-gated premium API access on Base network, pay $0.02 per request in USDC.","tagline":"x402-gated premium API access on Base network, pay $0.02 per request in USDC.","description":"This endpoint at lowpaymentfee.com provides \"Premium API Access\" via the x402 payment protocol on the Base network. The specific endpoint /api/v1/cards/21 is one of many API endpoints offered by this provider, all priced at $0.02 per request paid in USDC (USD Coin) with no API keys, rate limits, or commitments required.\n\nThe provider offers a broad catalog of endpoints spanning data & analytics (metrics, reports, data export, insights), AI & machine learning (sentiment analysis, text summarization, classification, embeddings), finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation). All endpoints use the same x402 payment model settled on the Base L2 network.\n\nThe specific functionality of /api/v1/cards/21 is not documented beyond the generic label \"Premium API Access.\" The endpoint accepts POST requests and returns application/json. The x402 challenge confirms it is live and requires a payment of 20,000 base units of USDC (6 decimals), equaling $0.02 per call. No OpenAPI schema, request/response examples, or detailed documentation were found for this specific endpoint.","tags":[],"capabilities":["x402-payment","usdc-settlement","base-network","pay-per-request","no-api-key","json-response","post-method"],"categories":["api-gateway","payments"],"synonyms":["low payment fee API","x402 API","micropayment API","pay-per-call API","Base USDC API","premium access endpoint"],"warnings":["No documentation available for the specific endpoint /api/v1/cards/21 — its actual functionality is unclear","All documentation pages (docs, api, pricing, README) returned only 'Connect wallet' with no content","No OpenAPI schema or request/response examples available","The label 'Premium API Access' is generic and does not describe what data or service is provided"],"endpointUrl":"https://lowpaymentfee.com/api/v1/cards/21","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/cards/21","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.350","qualityRationale":"The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base), but there is no documentation of what /api/v1/cards/21 actually returns, no request/response schema, and the crawled docs/pricing/README pages are all blank beyond a 'Connect wallet' prompt. The specific functionality is 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'0.02':11,26,65,182 '000':174 '20':173 '6':179 'Base USDC API' 'accept':155 'access':6,21,38,152 'ai':98 'analysi':102 'analyt':92 'api':5,20,37,56,75,151 'application/json':160 'base':8,23,46,135,175 'base-network' 'beyond':146 'broad':86 'call':184 'catalog':87 'challeng':163 'classif':105 'coin':72 'commit':80 'confirm':164 'convers':122 'data':91,95 'decim':180 'detail':191 'document':145,192 'embed':106 'endpoint':32,50,57,89,125,154,198 'equal':181 'estim':116 'exampl':189 'exchang':111 'export':96 'feed':110 'financ':107 'found':194 'function':140 'gas':115 'gate':3,18 'generat':123 'generic':148 'geocod':120 'infrastructur':118 'insight':97 'json-response' 'key':76 'l2':136 'label':149 'learn':100 'limit':78 'live':167 'low payment fee API' 'lowpaymentfee.com':34 'machin':99 'mani':55 'metric':93 'micropayment API' 'model':131 'network':9,24,47,137 'no-api-key' 'offer':58,84 'one':53 'openapi':186 'paid':68 'pay':10,25 'pay-per-call API' 'pay-per-request' 'payment':42,130,171 'per':12,27,66,183 'post':156 'post-method' 'premium':4,19,36,150 'premium access endpoint' 'price':63,109 'protocol':43 'provid':35,61,83 'quot':114 'rate':77,112 'report':94 'request':13,28,67,157 'request/response':188 'requir':81,169 'return':159 'schema':187 'sentiment':101 'settl':132 'span':90 'specif':49,139,197 'summar':104 'text':103 'token':113 'unit':176 'usd':71 'usdc':15,30,70,178 'usdc-settlement' 'use':126 'util':119 'valid':121 'via':39 'web3':108 'x402':2,17,41,129,162 'x402 API' 'x402-gated':1,16 'x402-payment'","prices":[{"id":"7b5db213-e5c0-444c-bde2-a5aca9ea4132","listingId":"12b79bab-a192-4544-873c-64ccdd51e7a6","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/cards/21","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:43:24.365Z"}],"sources":[{"listingId":"12b79bab-a192-4544-873c-64ccdd51e7a6","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/cards/21","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:43:24.365Z","lastSeenAt":"2026-04-24T08:02:54.425Z"}],"details":{"listingId":"12b79bab-a192-4544-873c-64ccdd51e7a6","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/cards/21 \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <x402_payment_token>\"","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"The endpoint returns a 402 challenge requiring 20000 base units of USDC on Base network","source_url":"https://lowpaymentfee.com/api/v1/cards/21"},{"claim":"All endpoints are priced at $0.02 per request with no API keys, rate limits, or minimums","source_url":"https://lowpaymentfee.com"},{"claim":"USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base","source_url":"https://lowpaymentfee.com/api/v1/cards/21"}],"useCases":["Accessing premium API data with per-request micropayments","Agent-driven API consumption without pre-registration or API keys","Programmatic pay-as-you-go access to various utility endpoints"],"bestFor":["Agents needing instant API access without signup","Developers testing x402 payment flows on Base","Low-volume consumers who prefer per-call pricing over subscriptions"],"notFor":["Users needing detailed documentation or guaranteed SLAs","High-volume use cases where per-request pricing becomes expensive","Anyone requiring non-crypto payment methods"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:27.389Z"},"updatedAt":"2026-04-24T08:02:54.425Z"}}