{"id":"e6169fa6-7291-444a-89d4-057e0704c670","shortId":"CPYkzs","kind":"x402","title":"Premium API access via x402 micropayment on Base — $0.02 per request in USDC.","tagline":"Premium API access via x402 micropayment on Base — $0.02 per request in USDC.","description":"This endpoint at lowpaymentfee.com provides \"Premium API Access\" gated by the x402 payment protocol. The provider's site advertises a broad catalog of pay-per-call APIs 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 are priced at $0.02 per request, settled in USDC on the Base network with no API keys, no rate limits, and no commitments required.\n\nThe specific endpoint probed (/api/v1/apikeys/71) returned a valid x402 challenge with maxAmountRequired of 20,000 base units of USDC (0x8335…2913 on Base, 6 decimals), which equals $0.02 USD — consistent with the advertised pricing. Payment is made via the x402 \"exact\" scheme to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3, with a 300-second timeout. The endpoint accepts POST requests and returns application/json.\n\nDocumentation is extremely thin: the /docs, /pricing, /api, and /README pages all render only a \"Connect wallet\" prompt with no further content. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available. The exact purpose of the /api/v1/apikeys/71 path (as opposed to the other listed endpoints) is unclear — it may generate or retrieve an API key. Without schema details or sample payloads, integrators will need to experiment to determine expected inputs and outputs.","tags":[],"capabilities":["x402-payment","usdc-base","pay-per-request","micropayment","api-key-generation","data-analytics","ai-inference","sentiment-analysis","text-summarization","classification","embeddings","finance-data","geocoding"],"categories":["api-gateway","ai","finance","infrastructure"],"synonyms":["x402 API","micropayment API","pay-per-call","USDC API access","Base network API","lowpaymentfee","premium API key"],"warnings":["No OpenAPI or schema documentation available — all doc pages render only 'Connect wallet'","The exact purpose and expected request body for /api/v1/apikeys/71 is undocumented","No response schema or example responses are available","The broad catalog of endpoints listed on the homepage cannot be individually verified from this probe"],"endpointUrl":"https://lowpaymentfee.com/api/v1/apikeys/71","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/apikeys/71","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 challenge with clear pricing ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond a wallet-connect prompt, and the specific purpose of /api/v1/apikeys/71 is ambiguous. This is effectively a stub 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'/api/v1/apikeys/71':119,214 '/docs':178 '/pricing':179 '/readme':182 '0.02':9,22,94,142 '000':129 '0x1a2b13e97f5f837c8f9fa1f95a1484b7c70d85f3':159 '0x8335':134 '20':128 '2913':135 '300':162 '6':138 'Base network API' 'USDC API access' 'accept':167 'access':3,16,34 'address':158 'advertis':45,147 'ai':63 'ai-inference' 'analysi':67 'analyt':57 'api':2,15,33,54,106,231 'api-key-generation' 'application/json':172 'avail':208 'base':8,21,102,130,137 'broad':47 'call':53 'catalog':48 'challeng':124 'classif':70 'classification' 'commit':113 'connect':188 'consist':144 'content':194 'convers':87 'data':56,60 'data-analytics' 'decim':139 'detail':235 'determin':245 'document':173,203 'embed':71 'embeddings' 'endpoint':28,90,117,166,222 'equal':141 'estim':81 'exact':155,210 'exampl':207 'exchang':76 'expect':246 'experi':243 'export':61 'extrem':175 'feed':75 'financ':72 'finance-data' 'gas':80 'gate':35 'generat':88,227 'geocod':85 'geocoding' 'infrastructur':83 'input':247 'insight':62 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Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T19:29:33.179Z"}],"sources":[{"listingId":"e6169fa6-7291-444a-89d4-057e0704c670","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/apikeys/71","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T19:29:33.179Z","lastSeenAt":"2026-04-22T05:31:51.889Z"}],"details":{"listingId":"e6169fa6-7291-444a-89d4-057e0704c670","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/apikeys/71 \\\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":"All endpoints priced at $0.02 per request with no API keys, no rate limits, instant access on Base network","source_url":"https://lowpaymentfee.com"},{"claim":"x402 challenge returns maxAmountRequired of 20000 base units USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base","source_url":"https://lowpaymentfee.com/api/v1/apikeys/71"},{"claim":"Provider advertises AI, analytics, finance, and infrastructure API categories","source_url":"https://lowpaymentfee.com"}],"useCases":["Acquiring API keys or premium access tokens via a single USDC micropayment","Programmatic pay-per-call access to AI inference endpoints (sentiment, summarization, classification, embeddings)","Fetching real-time financial data (prices, exchange rates, gas estimates) without subscription commitments","Agent-driven API consumption where each call is individually settled on-chain"],"bestFor":["Developers wanting zero-commitment, pay-as-you-go API access","AI agents that can settle x402 payments autonomously on Base","Projects needing low-cost micropayment-gated endpoints without API key management"],"notFor":["High-volume use cases where per-request on-chain settlement adds latency or cost overhead","Users who need detailed API documentation or guaranteed SLAs before integrating"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:28.972Z"},"updatedAt":"2026-04-22T05:31:51.889Z"}}