{"id":"2636abcb-419d-4d15-8d28-a7327bb972c6","shortId":"8FNtd2","kind":"x402","title":"Pay-per-call API platform on Base (USDC) offering data, AI, finance, and utility endpoints at $0.02/request.","tagline":"Pay-per-call API platform on Base (USDC) offering data, AI, finance, and utility endpoints at $0.02/request.","description":"lowpaymentfee.com is an x402-enabled API platform that provides a broad catalog of pay-per-request endpoints settled in USDC on the Base network. The specific endpoint `/api/v1/keys/21` is listed as \"Premium API Access\" and costs up to $0.02 per call (20,000 base units of USDC with 6 decimals). Payment is handled via the x402 protocol — no API keys, accounts, or subscriptions are required; callers attach an X-PAYMENT header with a signed USDC payment to each request.\n\nThe wider platform advertises four endpoint categories: 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 listed endpoints share the same $0.02/request pricing. The platform claims no rate limits and instant access.\n\nImportant caveat: the specific functionality behind `/api/v1/keys/21` (\"Premium API Access\") is not documented beyond its title. There is no OpenAPI schema, no request/response examples, and the crawled docs and pricing pages returned only a wallet-connect prompt with no additional detail. The endpoint is confirmed live (returns a valid x402 402 challenge), but what it actually returns upon successful payment is unknown from available materials.","tags":[],"capabilities":["x402-payment","usdc-settlement","base-network","pay-per-request","no-api-key","data-analytics","ai-inference","finance-data","utility-services"],"categories":["api-platform","llm","finance","geo"],"synonyms":["x402 API","pay-per-call API","USDC API","micropayment API","Base network API","lowpaymentfee","crypto-paid API"],"warnings":["No documentation available for the specific endpoint /api/v1/keys/21 — its actual functionality is unknown","No OpenAPI or JSON schema describing request parameters or response format","Crawled /api, /pricing, and /README pages returned no useful content (only wallet-connect prompts)","The platform lists many endpoint categories but none have documented schemas or example payloads"],"endpointUrl":"https://lowpaymentfee.com/api/v1/keys/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/keys/21","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.300","qualityRationale":"The endpoint is confirmed live via a valid x402 402 challenge, but there is no OpenAPI schema, no request/response examples, and no documentation explaining what /api/v1/keys/21 actually returns. The crawled pages beyond the homepage yielded only wallet-connect prompts. The listing is effectively a stub with pricing and liveness confirmed but functionality 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'lowpaymentfee' 'lowpaymentfee.com':39 'machin':136 'materi':244 'metric':130 'micropayment API' 'network':64 'no-api-key' 'offer':10,29 'openapi':198 'page':209 'pay':2,21,54 'pay-per-cal':1,20 'pay-per-call API' 'pay-per-request':53 'payment':91,111,117,239 'per':3,22,55,80 'platform':6,25,46,123,171 'premium':72,186 'price':146,169,208 'prompt':216 'protocol':97 'provid':48 'quot':151 'rate':149,174 'report':131 'request':56,120 'request/response':201 'requir':105 'return':210,226,236 'schema':199 'sentiment':138 'settl':58 'share':164 'sign':115 'specif':66,182 'subscript':103 'success':238 'summar':141 'text':140 'titl':194 'token':150 'unit':85 'unknown':241 'upon':237 'usdc':9,28,60,87,116 'usdc-settlement' 'util':15,34,156 'utility-services' 'valid':158,228 'via':94 'wallet':214 'wallet-connect':213 'web3':145 'wider':122 'x':110 'x-payment':109 'x402':43,96,229 'x402 API' 'x402-enabled':42 'x402-payment'","prices":[{"id":"83dac21c-5807-4913-bc57-f4f269f64198","listingId":"2636abcb-419d-4d15-8d28-a7327bb972c6","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/keys/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":"2026-04-21T18:32:23.468Z"}],"sources":[{"listingId":"2636abcb-419d-4d15-8d28-a7327bb972c6","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/keys/21","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:23.468Z","lastSeenAt":"2026-04-22T01:02:18.800Z"}],"details":{"listingId":"2636abcb-419d-4d15-8d28-a7327bb972c6","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/keys/21 \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <signed-x402-payment-header>\"","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"The endpoint returns a valid x402 402 challenge with maxAmountRequired of 20000 base units of USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/keys/21"},{"claim":"USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base network","source_url":"https://lowpaymentfee.com/api/v1/keys/21"},{"claim":"All listed endpoints priced at $0.02 per request with no API keys, no rate limits, and instant access","source_url":"https://lowpaymentfee.com"},{"claim":"Platform offers Data & Analytics, AI & ML, Finance & Web3, and Infrastructure endpoint categories","source_url":"https://lowpaymentfee.com"}],"useCases":["Agents that need on-demand API access without managing API keys or subscriptions","Paying per-call for AI inference (sentiment, summarization, classification, embeddings)","Fetching real-time financial data (prices, exchange rates, gas estimates) with crypto micropayments","Geocoding or data validation without account setup"],"bestFor":["AI agents or bots that can sign x402 payments autonomously","Developers who want zero-signup, pay-as-you-go API access","Use cases requiring very low per-call costs ($0.02) with no minimum commitment"],"notFor":["Users who need detailed API documentation or guaranteed SLAs before integrating","High-volume workloads where $0.02/request adds up and bulk pricing would be preferred","Callers who cannot transact in USDC on the Base network"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:05.767Z"},"updatedAt":"2026-04-22T01:02:18.800Z"}}