{"id":"841c0162-df81-4223-ae5e-f90fecc6d96e","shortId":"Bmmk7B","kind":"x402","title":"Pay-per-call API platform on Base with USDC payments via x402 — $0.02/request, no API keys required.","tagline":"Pay-per-call API platform on Base with USDC payments via x402 — $0.02/request, no API keys required.","description":"lowpaymentfee.com is a pay-per-request API platform that uses the x402 protocol to accept USDC payments on the Base network. The specific endpoint `/api/v1/invoices/13` is listed as \"Premium API Access\" and returns JSON. The x402 challenge indicates a max cost of 20,000 base units of USDC (0.02 USD per call), consistent with the site's advertised $0.02/request pricing across all endpoints.\n\nThe broader platform advertises multiple API categories including 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 uniformly at $0.02 per request with no API keys, no rate limits, and no minimum commitments.\n\nHowever, the specific functionality of the `/api/v1/invoices/13` endpoint is unclear — it does not appear in the site's listed API catalog, and the description \"Premium API Access\" is generic. Documentation pages (`/docs`, `/pricing`, `/README`) returned only a \"Connect wallet\" prompt with no substantive content. There is no OpenAPI schema, no request/response examples, and no detailed documentation available for any endpoint.","tags":[],"capabilities":["x402-payment","usdc-base","pay-per-request","json-response","no-api-key","invoice-api"],"categories":["api-platform","finance"],"synonyms":["low payment fee","x402 api","pay per call api","usdc api","base network api","micropayment api","invoice api"],"warnings":["The endpoint /api/v1/invoices/13 does not appear in the site's listed API catalog — its specific functionality is unknown.","No documentation is available: /docs, /pricing, /README, and /api all return only a 'Connect wallet' prompt with no substantive content.","No OpenAPI schema or request/response examples are provided for any endpoint.","The platform lists many API categories (AI, analytics, finance, infrastructure) but none can be verified for actual functionality from the crawl data."],"endpointUrl":"https://lowpaymentfee.com/api/v1/invoices/13","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/13","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.300","qualityRationale":"The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base), but there is no documentation, no OpenAPI schema, no request/response examples, and the specific purpose of /api/v1/invoices/13 is undocumented. All doc pages returned only 'Connect wallet' with no 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'/docs':196 '/pricing':197 '/readme':198 '/request':15,34,99 '0.02':14,33,88,98,151 '000':83 '20':82 'accept':54 'access':70,191 'across':101 'advertis':97,107 'ai':119 'analysi':123 'analyt':113 'api':5,17,24,36,46,69,109,156,184,190 'appear':178 'avail':221 'base':8,27,59,84 'base network api' 'broader':105 'call':4,23,91 'catalog':185 'categori':110 'challeng':76 'classif':126 'commit':164 'connect':202 'consist':92 'content':208 'convers':143 'cost':80 'data':112,116 'descript':188 'detail':219 'document':194,220 'embed':127 'endpoint':63,103,146,172,224 'estim':137 'exampl':216 'exchang':132 'export':117 'feed':131 'financ':128 'function':168 'gas':136 'generat':144 'generic':193 'geocod':141 'howev':165 'includ':111 'indic':77 'infrastructur':139 'insight':118 'invoice api' 'invoice-api' 'json':73 'json-response' 'key':18,37,157 'learn':121 'limit':160 'list':66,183 'low payment fee' 'lowpaymentfee.com':39 'machin':120 'max':79 'metric':114 'micropayment api' 'minimum':163 'multipl':108 'network':60 'no-api-key' 'openapi':212 'page':195 'pay':2,21,43 'pay per call api' 'pay-per-cal':1,20 'pay-per-request':42 'payment':11,30,56 'per':3,22,44,90,152 'platform':6,25,47,106 'premium':68,189 'price':100,130,148 'prompt':204 'protocol':52 'quot':135 'rate':133,159 'report':115 'request':45,153 'request/response':215 'requir':19,38 'return':72,199 'schema':213 'sentiment':122 'site':95,181 'specif':62,167 'substant':207 'summar':125 'text':124 'token':134 'unclear':174 'uniform':149 'unit':85 'usd':89 'usdc':10,29,55,87 'usdc api' 'usdc-base' 'use':49 'util':140 'valid':142 'via':12,31 'wallet':203 'web3':129 'x402':13,32,51,75 'x402 api' 'x402-payment'","prices":[{"id":"01ebf72e-d0c5-47e4-9987-b394883a508e","listingId":"841c0162-df81-4223-ae5e-f90fecc6d96e","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/13","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:32:20.726Z"}],"sources":[{"listingId":"841c0162-df81-4223-ae5e-f90fecc6d96e","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/invoices/13","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:32:20.726Z","lastSeenAt":"2026-04-25T07:02:17.775Z"}],"details":{"listingId":"841c0162-df81-4223-ae5e-f90fecc6d96e","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/invoices/13\n# Returns 402 with x402 payment challenge.\n# Include X-PAYMENT header with a valid x402 payment proof to access the resource.","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"The x402 challenge returns maxAmountRequired of 20000 base units of USDC on Base network","source_url":"https://lowpaymentfee.com/api/v1/invoices/13"},{"claim":"All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base network","source_url":"https://lowpaymentfee.com"},{"claim":"The platform advertises Data & Analytics, AI & ML, Finance & Web3, and Infrastructure API categories","source_url":"https://lowpaymentfee.com"},{"claim":"USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base","source_url":"https://lowpaymentfee.com/api/v1/invoices/13"}],"useCases":["Accessing premium API data with per-request USDC micropayments on Base","Agent-driven API consumption without pre-registration or API keys","Programmatic invoice retrieval or generation"],"bestFor":["Developers wanting zero-signup, pay-as-you-go API access","AI agents that can settle x402 payments autonomously","Users who prefer crypto micropayments over subscription billing"],"notFor":["Users needing detailed API documentation or OpenAPI specs before integrating","High-volume consumers who need bulk pricing or rate-limit guarantees","Anyone without a Base-compatible USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:59.958Z"},"updatedAt":"2026-04-25T07:02:17.775Z"}}