{"id":"69180aec-2a70-4d90-b6c0-95e94e392a76","shortId":"PBqcDr","kind":"x402","title":"Pay-per-call API platform on Base (USDC) covering data, AI, finance, and utility endpoints at $0.02/request.","tagline":"Pay-per-call API platform on Base (USDC) covering data, AI, finance, and utility endpoints at $0.02/request.","description":"lowpaymentfee.com is an x402-enabled API platform that offers a broad catalog of pay-per-request endpoints settled in USDC on the Base network. The specific endpoint at `/api/v1/invoices/21` is listed as \"Premium API Access\" and returns an x402 challenge requesting up to 20,000 base units of USDC (i.e., $0.02) per call. The platform advertises no API keys, no rate limits, and instant access — callers simply attach an x402 payment header to each request.\n\nThe site's landing page lists 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 price point.\n\nHowever, documentation is essentially absent — the /docs, /pricing, /api, and /README pages all render only a \"Connect wallet\" prompt with no further content. There is no OpenAPI schema, no request/response examples, and no description of what the `/api/v1/invoices/21` endpoint specifically returns. The endpoint is live (402 challenge confirmed), but without documentation it is unclear what payload to send or what response to expect.","tags":[],"capabilities":["x402-payment","usdc-settlement","base-network","pay-per-request","data-analytics","ai-inference","sentiment-analysis","text-summarization","classification","embeddings","finance-data","geocoding","utility-apis"],"categories":["api-platform","llm","finance","geo"],"synonyms":["low payment fee","x402 api","pay per call api","usdc api","base network api","micropayment api","lowpaymentfee"],"warnings":["No documentation available — /docs, /pricing, /api, and /README pages all render only 'Connect wallet'","No OpenAPI or schema definition found for any endpoint","The specific purpose of /api/v1/invoices/21 ('Premium API Access') is undocumented — unclear what it returns","The broad catalog of endpoints listed on the homepage cannot be verified for functionality"],"endpointUrl":"https://lowpaymentfee.com/api/v1/invoices/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/invoices/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 and returns a valid x402 challenge, but documentation is effectively nonexistent — all doc pages show only 'Connect wallet'. There is no OpenAPI schema, no request/response examples, and no explanation of what the invoices/21 endpoint actually does. The listing is largely a 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'/api/v1/invoices/21':69,205 '/docs':174 '/pricing':175 '/readme':178 '/request':19,38,165 '0.02':18,37,91,164 '000':85 '20':84 '402':213 'absent':172 'access':75,105 'advertis':96 'ai':12,31,132 'ai-inference' 'analysi':136 'analyt':126 'api':5,24,45,74,98 'attach':108 'base':8,27,63,86 'base network api' 'base-network' 'broad':50 'call':4,23,93 'caller':106 'catalog':51 'categori':124 'challeng':80,214 'classif':139 'classification' 'confirm':215 'connect':184 'content':190 'convers':156 'cover':10,29 'data':11,30,125,129 'data-analytics' 'descript':201 'document':169,218 'embed':140 'embeddings' 'enabl':44 'endpoint':16,35,57,67,123,160,206,210 'essenti':171 'estim':150 'exampl':198 'exchang':145 'expect':230 'export':130 'feed':144 'financ':13,32,141 'finance-data' 'four':122 'gas':149 'generat':157 'geocod':154 'geocoding' 'header':112 'howev':168 'i.e':90 'infrastructur':152 'insight':131 'instant':104 'key':99 'land':119 'learn':134 'limit':102 'list':71,121,159 'live':212 'low payment fee' 'lowpaymentfee' 'lowpaymentfee.com':39 'machin':133 'metric':127 'micropayment api' 'network':64 'offer':48 'openapi':194 'page':120,179 'pay':2,21,54 'pay per call api' 'pay-per-cal':1,20 'pay-per-request':53 'payload':223 'payment':111 'per':3,22,55,92 'platform':6,25,46,95 'point':167 'premium':73 'price':143,166 'prompt':186 'quot':148 'rate':101,146 'render':181 'report':128 'request':56,81,115 'request/response':197 'respons':228 'return':77,208 'schema':195 'send':225 'sentiment':135 'sentiment-analysis' 'settl':58 'share':161 'simpli':107 'site':117 'specif':66,207 'summar':138 'text':137 'text-summarization' 'token':147 'unclear':221 'unit':87 'usdc':9,28,60,89 'usdc api' 'usdc-settlement' 'util':15,34,153 'utility-apis' 'valid':155 'wallet':185 'web3':142 'without':217 'x402':43,79,110 'x402 api' 'x402-enabled':42 'x402-payment'","prices":[{"id":"0c64617d-22b2-4c08-bdfd-bff39fe3773a","listingId":"69180aec-2a70-4d90-b6c0-95e94e392a76","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/invoices/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":"2026-04-18T18:36:22.147Z"}],"sources":[{"listingId":"69180aec-2a70-4d90-b6c0-95e94e392a76","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/invoices/21","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:36:22.147Z","lastSeenAt":"2026-04-23T19:00:41.077Z"}],"details":{"listingId":"69180aec-2a70-4d90-b6c0-95e94e392a76","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/invoices/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 an x402 challenge requesting up to 20,000 base units of USDC ($0.02) on Base network","source_url":"https://lowpaymentfee.com/api/v1/invoices/21"},{"claim":"The platform lists endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories all at $0.02/request","source_url":"https://lowpaymentfee.com"},{"claim":"The site advertises no API keys, no rate limits, and instant access","source_url":"https://lowpaymentfee.com"},{"claim":"Documentation pages (/docs, /pricing, /api, /README) render only 'Connect wallet'","source_url":"https://lowpaymentfee.com/docs"}],"useCases":["Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key management","Fetching real-time financial data such as token quotes, gas estimates, and exchange rates","Running utility operations like geocoding, validation, and data conversion on a per-call payment basis"],"bestFor":["Developers who want zero-signup, pay-as-you-go API access","Agents that can settle USDC payments on Base via x402","Projects needing low-cost micropayment-gated endpoints"],"notFor":["Users who need detailed API documentation or OpenAPI specs before integrating","Applications requiring high-throughput bulk access with negotiated pricing","Teams that cannot transact in USDC on the Base network"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:48.024Z"},"updatedAt":"2026-04-23T19:00:41.077Z"}}