{"id":"c459d8f8-2d98-4cc3-bbe6-76bbf858d13f","shortId":"yHn64G","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 collection of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and general utility services. All endpoints are paid per-request using USDC on the Base network via the x402 protocol — no API keys, no rate limits, and no subscriptions required.\n\nThe specific endpoint at `/api/v1/keys/13` is listed as \"Premium API Access\" and requires a payment of up to 20,000 base units of USDC (i.e., $0.02) per call, consistent with the platform's uniform $0.02/request pricing. The platform advertises categories including metrics, reports, data export, insights, sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and generation — though the exact functionality behind this particular `/keys/13` endpoint is not documented beyond its \"Premium API Access\" label.\n\nThe endpoint is live and returns a valid x402 challenge (HTTP 402) with payment details specifying USDC on Base (contract `0x8335…2913`). The platform's landing page loads successfully (HTTP 200), but deeper documentation pages (/api, /pricing, /README) all resolve to a minimal \"Connect wallet\" prompt with no additional technical detail. No OpenAPI spec, request/response schemas, or usage examples are provided, making it difficult to determine what data or functionality this specific endpoint returns.","tags":[],"capabilities":["x402-payment","per-request-billing","usdc-base","no-api-key","pay-per-use","data-analytics","ai-inference","finance-data","utility-services"],"categories":["api-platform","finance","llm","geo"],"synonyms":["pay-per-call API","x402 API","USDC API","micropayment API","low fee API","Base network API","crypto-paid API"],"warnings":["No OpenAPI or schema documentation available for any endpoint","The specific functionality of /api/v1/keys/13 is undocumented — 'Premium API Access' is the only description","Documentation pages (/api, /pricing, /README) all resolve to a minimal 'Connect wallet' page with no useful content","No request or response examples are available; integration requires trial-and-error"],"endpointUrl":"https://lowpaymentfee.com/api/v1/keys/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/keys/13","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 there is no OpenAPI spec, no request/response schema, no documentation beyond a landing page listing, and the specific purpose of /api/v1/keys/13 ('Premium API Access') is undefined. Deeper pages return only 'Connect wallet' with no 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'/api/v1/keys/13':95 '/keys/13':164 '/pricing':211 '/readme':212 '/request':19,38,126 '0.02':18,37,116,125 '000':110 '0x8335':195 '20':109 '200':205 '2913':196 '402':186 'Base network API' 'USDC API' 'access':101,173 'addit':223 'advertis':130 'ai':12,31 'ai-inference' 'ai/ml':56 'analysi':139 'analyt':55 'api':5,24,45,82,100,172 'base':8,27,75,111,193 'behind':161 'beyond':169 'call':4,23,118 'categori':131 'challeng':184 'classif':142 'collect':50 'connect':218 'consist':119 'contract':194 'convers':154 'crypto-paid API' 'data':11,30,54,59,135,242 'data-analytics' 'deeper':207 'detail':189,225 'determin':240 'difficult':238 'document':168,208 'embed':143 'enabl':44 'endpoint':16,35,52,65,93,165,176,247 'estim':151 'exact':159 'exampl':233 'exchang':146 'export':136 'feed':145 'financ':13,32 'finance-data' 'finance/web3':58 'function':160,244 'gas':150 'general':61 'generat':156 'geocod':152 'http':185,204 'i.e':115 'includ':132 'infer':57 'insight':137 'key':83 'label':174 'land':200 'limit':86 'list':97 'live':178 'load':202 'low fee API' 'lowpaymentfee.com':39 'make':236 'metric':133 'micropayment API' 'minim':217 'network':76 'no-api-key' 'offer':10,29 'openapi':227 'page':201,209 'paid':67 'particular':163 'pay':2,21 'pay-per-cal':1,20 'pay-per-call API' 'pay-per-use' 'payment':105,188 'per':3,22,69,117 'per-request':68 'per-request-billing' 'platform':6,25,46,122,129,198 'premium':99,171 'price':127,144 'prompt':220 'protocol':80 'provid':48,235 'quot':149 'rate':85,147 'report':134 'request':70 'request/response':229 'requir':90,103 'resolv':214 'return':180,248 'schema':230 'sentiment':138 'servic':63 'span':53 'spec':228 'specif':92,246 'specifi':190 'subscript':89 'success':203 'summar':141 'technic':224 'text':140 'though':157 'token':148 'uniform':124 'unit':112 'usag':232 'usdc':9,28,72,114,191 'usdc-base' 'use':71 'util':15,34,62 'utility-services' 'valid':153,182 'via':77 'wallet':219 'x402':43,79,183 'x402 API' 'x402-enabled':42 'x402-payment'","prices":[{"id":"f5b161fc-7521-49d6-91f4-0defef666f1f","listingId":"c459d8f8-2d98-4cc3-bbe6-76bbf858d13f","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/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":"2026-04-21T18:32:23.293Z"}],"sources":[{"listingId":"c459d8f8-2d98-4cc3-bbe6-76bbf858d13f","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/keys/13","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:23.293Z","lastSeenAt":"2026-04-22T01:02:18.543Z"}],"details":{"listingId":"c459d8f8-2d98-4cc3-bbe6-76bbf858d13f","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/keys/13 \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <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 challenge with maxAmountRequired of 20000 base units of USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/keys/13"},{"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":"Pricing is $0.02/request with no API keys, no rate limits, and instant access on Base network","source_url":"https://lowpaymentfee.com"},{"claim":"USDC contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","source_url":"https://lowpaymentfee.com/api/v1/keys/13"}],"useCases":["Accessing AI inference (sentiment, summarization, classification, embeddings) without subscriptions","Fetching real-time finance data (prices, exchange rates, gas estimates) on a per-call basis","Running utility operations (geocoding, validation, conversion) with instant crypto payment","Integrating pay-per-use data analytics into agent workflows"],"bestFor":["Developers wanting subscription-free, pay-as-you-go API access","AI agents that can settle payments via x402 on Base","Projects needing low-cost micro-transactions for API calls"],"notFor":["Users who need detailed API documentation or OpenAPI specs before integrating","High-volume consumers who prefer flat-rate or subscription pricing","Developers without USDC on the Base network"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:06.021Z"},"updatedAt":"2026-04-22T01:02:18.543Z"}}