{"id":"168086de-ec65-4be2-ade3-42efc897c271","shortId":"kV23y4","kind":"x402","title":"Pay-per-call API platform on Base with $0.02 USDC requests via x402 — no API keys required.","tagline":"Pay-per-call API platform on Base with $0.02 USDC requests via x402 — 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/37` is listed as \"Premium API Access\" and returns a 402 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 X-PAYMENT header with a valid x402 payment proof.\n\nThe broader platform offers endpoints across four 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 endpoints are listed at $0.02 per request.\n\nThis particular endpoint (`/api/v1/invoices/37`) is labeled \"Premium API Access\" but no further documentation describes what data or functionality it returns. The docs, pricing, API, and README pages all render only a \"Connect wallet\" prompt with no additional content. Without schema details or response examples, the actual behavior of this endpoint remains unclear.","tags":[],"capabilities":["x402-payment","usdc-base-network","pay-per-request","no-api-key","json-response","post-method"],"categories":["api-platform","finance"],"synonyms":["low payment fee","x402 api","micropayment api","usdc api access","pay per call api","base network api","invoice api"],"warnings":["No documentation available — docs, pricing, API, and README pages all show only 'Connect wallet' with no content.","No OpenAPI or output schema provided; the actual response payload of /api/v1/invoices/37 is unknown.","The endpoint name 'Premium API Access' is generic and does not describe what data or functionality is returned.","Multiple other endpoints are advertised on the landing page but none have documented schemas or examples."],"endpointUrl":"https://lowpaymentfee.com/api/v1/invoices/37","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/37","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.300","qualityRationale":"The endpoint is live and returns a valid x402 402 challenge, but there is no documentation, no OpenAPI schema, no response examples, and no description of what the endpoint actually returns. The docs/pricing/API pages are all blank beyond a wallet-connect prompt. The listing is effectively a 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'0.02':10,28,84,159 '000':78 '20':77 '402':72 'accept':52 'access':68,98,170 'across':118 'actual':207 'addit':198 'advertis':89 'ai':128 'analysi':132 'analyt':122 'api':5,16,23,34,44,67,91,169,185 'attach':101 'base':8,26,57,79 'base network api' 'behavior':208 'broader':114 'call':4,22,86 'caller':99 'categori':120 'challeng':73 'classif':135 'connect':193 'content':199 'convers':152 'data':121,125,177 'describ':175 'detail':202 'doc':183 'document':174 'embed':136 'endpoint':61,117,155,164,211 'estim':146 'exampl':205 'exchang':141 'export':126 'feed':140 'financ':137 'four':119 'function':179 'gas':145 'generat':153 'geocod':150 'header':106 'i.e':83 'infrastructur':148 'insight':127 'instant':97 'invoice api' 'json-response' 'key':17,35,92 'label':167 'learn':130 'limit':95 'list':64,157 'low payment fee' 'lowpaymentfee.com':37 'machin':129 'metric':123 'micropayment api' 'network':58 'no-api-key' 'offer':116 'page':188 'particular':163 'pay':2,20,41 'pay per call api' 'pay-per-cal':1,19 'pay-per-request':40 'payment':54,105,111 'per':3,21,42,85,160 'platform':6,24,45,88,115 'post-method' 'premium':66,168 'price':139,184 'prompt':195 'proof':112 'protocol':50 'quot':144 'rate':94,142 'readm':187 'remain':212 'render':190 'report':124 'request':12,30,43,74,161 'requir':18,36 'respons':204 'return':70,181 'schema':201 'sentiment':131 'simpli':100 'specif':60 'summar':134 'text':133 'token':143 'unclear':213 'unit':80 'usdc':11,29,53,82 'usdc api access' 'usdc-base-network' 'use':47 'util':149 'valid':109,151 'via':13,31 'wallet':194 'web3':138 'without':200 'x':104 'x-payment':103 'x402':14,32,49,110 'x402 api' 'x402-payment'","prices":[{"id":"e70ffa9a-7bbe-4539-bb7f-6546cbcc8996","listingId":"168086de-ec65-4be2-ade3-42efc897c271","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/37","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:38:31.597Z"}],"sources":[{"listingId":"168086de-ec65-4be2-ade3-42efc897c271","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/invoices/37","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:38:31.597Z","lastSeenAt":"2026-04-24T21:31:38.277Z"}],"details":{"listingId":"168086de-ec65-4be2-ade3-42efc897c271","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/invoices/37 \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <x402-payment-proof>\"","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"The endpoint returns a 402 challenge requesting up to 20,000 base units of USDC ($0.02) on Base network.","source_url":"https://lowpaymentfee.com/api/v1/invoices/37"},{"claim":"The platform advertises $0.02 per request with no API keys, no rate limits, and instant access.","source_url":"https://lowpaymentfee.com"},{"claim":"USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913.","source_url":"https://lowpaymentfee.com/api/v1/invoices/37"},{"claim":"The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories.","source_url":"https://lowpaymentfee.com"}],"useCases":["Programmatic access to premium API data with per-call USDC micropayments","Agent-driven workflows that need keyless, on-demand API access","Testing x402 payment flows against a live endpoint on Base"],"bestFor":["Developers experimenting with x402 payment protocol","AI agents that can settle USDC payments on Base","Users who want pay-as-you-go access without subscriptions or API keys"],"notFor":["Users who need detailed API documentation or response schemas before integrating","High-volume consumers who prefer flat-rate or subscription pricing","Anyone without a Base-compatible USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:41.6Z"},"updatedAt":"2026-04-24T21:31:38.277Z"}}