{"id":"2b7324d1-2c98-49c5-b6c5-d7ffa2215fe1","shortId":"F4ejAz","kind":"x402","title":"Pay-per-call API suite on Base via x402 — data, AI, finance, and utility endpoints at $0.02/request.","tagline":"Pay-per-call API suite on Base via x402 — data, AI, finance, and utility endpoints at $0.02/request.","description":"lowpaymentfee.com offers a collection of pay-per-request API endpoints accessible via the x402 payment protocol on the Base network. The specific endpoint at `/api/v1/transactions/4` is labeled \"Premium API Access\" and accepts POST requests, settling payments in USDC (contract 0x8335…2913 on Base). The x402 challenge indicates a maximum amount of 20,000 base units, which at 6 decimals for USDC equals $0.02 per request.\n\nThe provider's landing page advertises four categories of APIs: 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 with no API keys, no rate limits, and no minimum commitments required.\n\nDocumentation beyond the landing page is extremely sparse — the docs, API, pricing, and README pages all render only a \"Connect wallet\" prompt with no additional technical detail. There is no OpenAPI schema, no request/response examples, and no description of what the `/api/v1/transactions/4` endpoint specifically returns. The exact purpose of this particular endpoint (as opposed to the named endpoints on the homepage) is unclear.","tags":[],"capabilities":["x402-payment","pay-per-request","usdc-settlement","base-network","data-analytics","ai-inference","sentiment-analysis","text-summarization","classification","embeddings","finance-data","geocoding","no-api-key"],"categories":["api-marketplace","llm","finance","geo"],"synonyms":["low payment fee","x402 api","pay per call api","micropayment api","base usdc api","cheap api access","no-auth api"],"warnings":["No OpenAPI or schema documentation available for any endpoint","The specific endpoint /api/v1/transactions/4 is not listed among the named APIs on the homepage — its exact function is unknown","All documentation pages (docs, API, pricing, README) render only 'Connect wallet' with no usable content","No request or response examples are available anywhere in the crawled material"],"endpointUrl":"https://lowpaymentfee.com/api/v1/transactions/4","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/4","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.350","qualityRationale":"The endpoint is live (402 challenge captured) and pricing is clear ($0.02 USDC on Base), but there is no OpenAPI schema, no request/response examples, and no documentation beyond a landing page listing. The specific purpose of /api/v1/transactions/4 is undocumented. Docs pages return only 'Connect wallet' with no 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'/request':19,38 '0.02':18,37,102,153 '000':92 '0x8335':79 '20':91 '2913':80 '6':97 'accept':71 'access':50,69 'addit':192 'advertis':110 'ai':12,31,122 'ai-inference' 'amount':89 'analysi':126 'analyt':116 'api':5,24,48,68,114,158,178 'base':8,27,58,82,93 'base usdc api' 'base-network' 'beyond':169 'call':4,23 'categori':112 'challeng':85 'cheap api access' 'classif':129 'classification' 'collect':42 'commit':166 'connect':187 'contract':78 'convers':146 'data':11,30,115,119 'data-analytics' 'decim':98 'descript':205 'detail':194 'doc':177 'document':168 'embed':130 'embeddings' 'endpoint':16,35,49,62,149,210,219,225 'equal':101 'estim':140 'exact':214 'exampl':202 'exchang':135 'export':120 'extrem':174 'feed':134 'financ':13,32,131 'finance-data' 'four':111 'gas':139 'generat':147 'geocod':144 'geocoding' 'homepag':228 'indic':86 'infrastructur':142 'insight':121 'key':159 'label':66 'land':108,171 'learn':124 'limit':162 'list':151 'low payment fee' 'lowpaymentfee.com':39 'machin':123 'maximum':88 'metric':117 'micropayment api' 'minimum':165 'name':224 'network':59 'no-api-key' 'no-auth api' 'offer':40 'openapi':198 'oppos':221 'page':109,172,182 'particular':218 'pay':2,21,45 'pay per call api' 'pay-per-cal':1,20 'pay-per-request':44 'payment':54,75 'per':3,22,46,103,154 'post':72 'premium':67 'price':133,179 'prompt':189 'protocol':55 'provid':106 'purpos':215 'quot':138 'rate':136,161 'readm':181 'render':184 'report':118 'request':47,73,104,155 'request/response':201 'requir':167 'return':212 'schema':199 'sentiment':125 'sentiment-analysis' 'settl':74 'spars':175 'specif':61,211 'suit':6,25 'summar':128 'technic':193 'text':127 'text-summarization' 'token':137 'unclear':230 'unit':94 'usdc':77,100 'usdc-settlement' 'util':15,34,143 'valid':145 'via':9,28,51 'wallet':188 'web3':132 'x402':10,29,53,84 'x402 api' 'x402-payment'","prices":[{"id":"8aac15a5-138a-4bee-840b-985199c7ea7b","listingId":"2b7324d1-2c98-49c5-b6c5-d7ffa2215fe1","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/4","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T19:26:42.956Z"}],"sources":[{"listingId":"2b7324d1-2c98-49c5-b6c5-d7ffa2215fe1","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/transactions/4","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T19:26:42.956Z","lastSeenAt":"2026-04-22T16:32:13.454Z"}],"details":{"listingId":"2b7324d1-2c98-49c5-b6c5-d7ffa2215fe1","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/transactions/4 \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <x402-payment-token>\"","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 in USDC (6 decimals) = $0.02 on Base network","source_url":"https://lowpaymentfee.com/api/v1/transactions/4"},{"claim":"The landing page lists endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories all at $0.02/request","source_url":"https://lowpaymentfee.com"},{"claim":"The site advertises no API keys, no rate limits, instant access, and Base network settlement","source_url":"https://lowpaymentfee.com"},{"claim":"USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base","source_url":"https://lowpaymentfee.com/api/v1/transactions/4"}],"useCases":["Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key management","Fetching real-time financial data such as token quotes, gas estimates, and exchange rates on a per-call basis","Running utility operations like geocoding, validation, and data conversion with instant crypto-settled payments","Integrating pay-as-you-go data analytics into agent workflows"],"bestFor":["Developers wanting zero-signup, pay-per-request API access","AI agents that can settle x402 payments in USDC on Base","Projects needing low-cost micropayment-gated endpoints without rate limits"],"notFor":["Users who need detailed API documentation or OpenAPI schemas before integrating","Applications requiring high-volume bulk pricing or subscription plans","Users without a Base-compatible USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:37.126Z"},"updatedAt":"2026-04-22T16:32:13.454Z"}}