{"id":"d9b6690a-8e2f-4af6-97eb-f013b64937d3","shortId":"xqR7jk","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 an x402-enabled API platform that offers a broad set of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities. Every endpoint costs $0.02 per request, paid in USDC on the Base network with no API keys, no rate limits, and no commitments required. The specific endpoint at `/api/v1/transactions/240` is listed as \"Premium API Access\" and returns a 402 challenge requesting up to 20,000 base units of USDC (i.e., $0.02 given USDC's 6 decimals) on Base.\n\nThe platform advertises 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 (geocoding, validation, conversion, generation). All endpoints follow the x402 payment protocol: callers receive a 402 challenge with payment details, settle in USDC on Base, and then gain access to the response.\n\nDocumentation is extremely sparse — the /docs, /api, /pricing, and /README pages all render only a \"Connect wallet\" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawled material. The actual behavior and output of the `/api/v1/transactions/240` endpoint is unknown beyond its x402 challenge metadata.","tags":[],"capabilities":["x402-payment","usdc-base-network","pay-per-request","data-analytics","ai-sentiment","ai-summarization","ai-classification","ai-embeddings","finance-price-feeds","exchange-rates","crypto-gas-estimates","geocoding","validation","conversion"],"categories":["llm","finance","geo","infrastructure"],"synonyms":["low payment fee","x402 API","pay per call API","USDC API","Base network API","micropayment API","crypto API gateway"],"warnings":["No OpenAPI specification or request/response schema available","All documentation pages (/docs, /api, /pricing, /README) render only 'Connect wallet' with no technical content","The specific purpose and output of /api/v1/transactions/240 ('Premium API Access') is undocumented — it is unclear what data or service it provides","No usage examples or error documentation found"],"endpointUrl":"https://lowpaymentfee.com/api/v1/transactions/240","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/240","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 with clear pricing ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond a landing page listing, and no examples. The actual functionality of the /api/v1/transactions/240 'Premium API Access' endpoint is entirely 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'/api/v1/transactions/240':84,226 '/docs':183 '/pricing':185 '/readme':187 '/request':13,28 '0.02':12,27,59,106 '000':100 '20':99 '402':94,161 '6':110 'Base network API' 'USDC API' 'access':90,174 'actual':220 'advertis':116 'ai':126 'ai-classification' 'ai-embeddings' 'ai-sentiment' 'ai-summarization' 'ai/ml':49 'analysi':130 'analyt':48,120 'api':5,20,37,71,89 'avail':214 'base':8,23,67,101,113,170 'behavior':221 'beyond':230 'broad':42 'call':4,19 'caller':158 'categori':117 'challeng':95,162,233 'classif':133 'commit':78 'connect':193 'convers':149 'conversion' 'cost':58 'crawl':217 'crypto API gateway' 'crypto-gas-estimates' 'data':47,52,119,123 'data-analytics' 'decim':111 'detail':165,200 'document':178,209 'embed':134 'enabl':36 'endpoint':45,57,82,152,227 'estim':144 'everi':56 'exampl':213 'exchang':139 'exchange-rates' 'export':124 'extrem':180 'feed':138 'financ':135 'finance-price-feeds' 'finance/web3':51 'follow':153 'gain':173 'gas':143 'generat':150 'geocod':147 'geocoding' 'given':107 'i.e':105 'includ':118 'infer':50 'infrastructur':54,146 'insight':125 'key':72 'learn':128 'limit':75 'list':86 'low payment fee' 'lowpaymentfee.com':31 'machin':127 'materi':218 'metadata':234 'metric':121 'micropayment API' 'network':9,24,68 'offer':40 'openapi':204 'output':223 'page':188 'paid':62 'pay':2,17 'pay per call API' 'pay-per-cal':1,16 'pay-per-request' 'payment':156,164 'per':3,18,60 'platform':6,21,38,115 'premium':88 'price':137 'prompt':195 'protocol':157 'quot':142 'rate':74,140 'receiv':159 'render':190 'report':122 'request':61,96 'request/response':207 'requir':79 'respons':177 'return':92 'schema':208 'sentiment':129 'set':43 'settl':166 'span':46 'spars':181 'spec':205 'specif':81 'summar':132 'technic':199 'text':131 'token':141 'unit':102 'unknown':229 'usag':212 'usdc':15,30,64,104,108,168 'usdc-base-network' 'util':55 'valid':148 'validation' 'via':10,25 'wallet':194 'web3':136 'x402':11,26,35,155,232 'x402 API' 'x402-enabled':34 'x402-payment'","prices":[{"id":"51144f82-1dd9-4efc-8a03-f478b158e9c4","listingId":"d9b6690a-8e2f-4af6-97eb-f013b64937d3","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/240","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:59:26.454Z"}],"sources":[{"listingId":"d9b6690a-8e2f-4af6-97eb-f013b64937d3","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/transactions/240","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:59:26.454Z","lastSeenAt":"2026-04-22T21:31:38.180Z"}],"details":{"listingId":"d9b6690a-8e2f-4af6-97eb-f013b64937d3","quickStartSnippet":"# x402 flow: POST to the endpoint, receive 402 challenge, pay USDC on Base, re-send with X-PAYMENT header\ncurl -X POST https://lowpaymentfee.com/api/v1/transactions/240 \\\n  -H 'Content-Type: application/json'","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"All endpoints cost $0.02 per request with no API keys, no rate limits, and instant access on Base network","source_url":"https://lowpaymentfee.com"},{"claim":"The x402 challenge for /api/v1/transactions/240 requests maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base","source_url":"https://lowpaymentfee.com/api/v1/transactions/240"},{"claim":"Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure","source_url":"https://lowpaymentfee.com"}],"useCases":["Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key management","Fetching real-time financial data like token quotes, exchange rates, and gas estimates on a per-call basis","Running utility operations such as geocoding, validation, and data conversion with instant crypto-settled payments"],"bestFor":["Developers who want zero-signup, pay-per-use API access settled in USDC on Base","Agents and bots that can autonomously pay for API calls via x402 protocol","Projects needing a variety of lightweight API services at a flat $0.02/call rate"],"notFor":["Users who need detailed API documentation, schemas, or guaranteed SLAs before integrating","Teams requiring high-volume bulk pricing or subscription-based access"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:41.252Z"},"updatedAt":"2026-04-22T21:31:38.180Z"}}