{"id":"8a42edcb-8f6d-4a42-afdf-bb557f343c86","shortId":"MJJ7R5","kind":"x402","title":"Pay-per-call API platform on Base network via x402 — $0.02/request in USDC.","tagline":"Pay-per-call API platform on Base network via x402 — $0.02/request in USDC.","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/transactions/16` is listed as \"Premium API Access\" and returns a 402 challenge requiring payment of up to 20,000 base units of USDC (i.e., $0.02) per call. No API keys or rate limits are required; callers simply attach an X-PAYMENT header with a valid x402 payment proof.\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 at $0.02 per request.\n\nHowever, the specific functionality behind `/api/v1/transactions/16` is not documented beyond the label \"Premium API Access.\" The crawled docs, pricing, and README pages all returned only a \"Connect wallet\" prompt with no additional content. There is no OpenAPI schema, no request/response examples, and no detailed documentation available for this or any other endpoint on the platform. The endpoint is live and responds with a valid x402 challenge, but what data or service it actually returns upon successful payment is unknown.","tags":[],"capabilities":["x402-payment","usdc-base-network","pay-per-request","no-api-key","no-rate-limit","json-response"],"categories":["api-platform","crypto"],"synonyms":["x402 API","pay-per-call API","USDC micropayment API","Base network API","lowpaymentfee","premium API access","crypto-paid API"],"warnings":["The actual data or service returned by /api/v1/transactions/16 upon successful payment is completely undocumented.","All documentation pages (docs, pricing, README, api) returned only 'Connect wallet' with no useful content.","No OpenAPI schema or request/response examples are available for any endpoint on the platform.","The platform lists many API categories (AI, analytics, finance, etc.) but provides no evidence these endpoints return real data."],"endpointUrl":"https://lowpaymentfee.com/api/v1/transactions/16","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/transactions/16","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.250","qualityRationale":"The endpoint is live and returns a valid x402 challenge, but there is no documentation, no OpenAPI schema, no request/response examples, and the actual functionality behind 'Premium API Access' is completely undocumented. The docs, pricing, and README pages are all empty beyond a wallet-connect prompt. This is effectively a stub 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'/request':13,28 '0.02':12,27,80,151 '000':74 '20':73 '402':66 'Base network API' 'USDC micropayment API' 'accept':46 'access':62,168 'actual':226 'addit':185 'advertis':108 'ai':120 'analysi':124 'analyt':114 'api':5,20,38,61,84,110,167 'attach':93 'avail':199 'base':8,23,51,75 'behind':158 'beyond':163 'broader':106 'call':4,19,82 'caller':91 'categori':111 'challeng':67,219 'classif':127 'connect':180 'content':186 'convers':144 'crawl':170 'crypto-paid API' 'data':113,117,222 'detail':197 'doc':171 'document':162,198 'embed':128 'endpoint':55,147,205,210 'estim':138 'exampl':194 'exchang':133 'export':118 'feed':132 'financ':129 'function':157 'gas':137 'generat':145 'geocod':142 'header':98 'howev':154 'i.e':79 'includ':112 'infrastructur':140 'insight':119 'json-response' 'key':85 'label':165 'learn':122 'limit':88 'list':58 'live':212 'lowpaymentfee' 'lowpaymentfee.com':31 'machin':121 'metric':115 'multipl':109 'network':9,24,52 'no-api-key' 'no-rate-limit' 'openapi':190 'page':175 'pay':2,17,35 'pay-per-cal':1,16 'pay-per-call API' 'pay-per-request':34 'payment':48,69,97,103,230 'per':3,18,36,81,152 'platform':6,21,39,107,208 'premium':60,166 'premium API access' 'price':131,149,172 'prompt':182 'proof':104 'protocol':44 'quot':136 'rate':87,134 'readm':174 'report':116 'request':37,153 'request/response':193 'requir':68,90 'respond':214 'return':64,177,227 'schema':191 'sentiment':123 'servic':224 'simpli':92 'specif':54,156 'success':229 'summar':126 'text':125 'token':135 'unit':76 'unknown':232 'upon':228 'usdc':15,30,47,78 'usdc-base-network' 'use':41 'util':141 'valid':101,143,217 'via':10,25 'wallet':181 'web3':130 'x':96 'x-payment':95 'x402':11,26,43,102,218 'x402 API' 'x402-payment'","prices":[{"id":"6c2157ce-eadb-4d79-b048-9f93706b509e","listingId":"8a42edcb-8f6d-4a42-afdf-bb557f343c86","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/transactions/16","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:58:44.299Z"}],"sources":[{"listingId":"8a42edcb-8f6d-4a42-afdf-bb557f343c86","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/transactions/16","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:58:44.299Z","lastSeenAt":"2026-04-23T19:01:44.876Z"}],"details":{"listingId":"8a42edcb-8f6d-4a42-afdf-bb557f343c86","quickStartSnippet":"# The endpoint requires an x402 X-PAYMENT header with a valid payment proof.\n# First, fetch the 402 challenge:\ncurl -X POST https://lowpaymentfee.com/api/v1/transactions/16\n# Then construct and attach the X-PAYMENT header per x402 spec\n# paying up to $0.02 USDC on Base to 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"Endpoint returns 402 with x402 challenge requiring up to 20,000 base units of USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/transactions/16"},{"claim":"USDC asset contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base network","source_url":"https://lowpaymentfee.com/api/v1/transactions/16"},{"claim":"Platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access","source_url":"https://lowpaymentfee.com"},{"claim":"Multiple API categories listed: Data & Analytics, AI & ML, Finance & Web3, Infrastructure","source_url":"https://lowpaymentfee.com"}],"useCases":["Accessing premium API data with per-request USDC micropayments on Base","Integrating pay-as-you-go API calls into agent workflows without API key management","Testing x402 protocol payment flows against a live endpoint"],"bestFor":["Developers experimenting with x402 payment protocol","Agents needing keyless, pay-per-call API access on Base","Low-volume consumers who prefer no subscription commitments"],"notFor":["Users who need detailed API documentation before purchasing","High-volume consumers who need bulk pricing or rate guarantees","Anyone without a Base-network USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:43.256Z"},"updatedAt":"2026-04-23T19:01:44.876Z"}}