{"id":"1fd0e8c8-ceba-452d-b4f8-039f4da2ff80","shortId":"pKX6W2","kind":"x402","title":"x402-gated API suite on Base: analytics, AI, finance, and utility endpoints at $0.02/request.","tagline":"x402-gated API suite on Base: analytics, AI, finance, and utility endpoints at $0.02/request.","description":"lowpaymentfee.com offers a collection of pay-per-call API endpoints gated by the x402 protocol on the Base network. The specific endpoint at `/api/v1/charges/185` is labeled \"Premium API Access\" and accepts payment in USDC (contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base. The maximum amount required per call is 20,000 base units of USDC (6 decimals), which equals $0.02 USD. No API keys, rate limits, or upfront commitments are needed — each request is individually settled on-chain.\n\nThe broader platform advertises four categories of endpoints: 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 listed endpoints share the same $0.02/request pricing. However, the crawled documentation pages (docs, pricing, API reference) returned only a wallet-connect prompt with no substantive content, so the actual behavior, input/output schemas, and data sources behind these endpoints remain undocumented.\n\nBecause this specific endpoint (`/charges/185`) is titled generically as \"Premium API Access\" without further description, it is unclear what data or functionality it returns. The x402 challenge is live and well-formed, confirming the endpoint is operational, but the lack of documentation means callers must experiment to discover the response format.","tags":[],"capabilities":["x402-payment","usdc-base","pay-per-request","data-analytics","ai-inference","sentiment-analysis","text-summarization","classification","embeddings","finance-data","geocoding","utility-apis"],"categories":["api-marketplace","llm","finance","geo"],"synonyms":["low payment fee","x402 API","pay-per-call API","Base USDC API","micropayment API","on-chain API access","402 payment required"],"warnings":["No documentation available — docs, pricing, and API reference pages all return only a wallet-connect prompt with no content.","The specific endpoint /api/v1/charges/185 has no description beyond 'Premium API Access'; its actual functionality is unknown.","No input or output schema is provided; callers must discover the API contract experimentally.","The platform lists many endpoint categories (AI, finance, analytics, utilities) but none have documented schemas or example responses."],"endpointUrl":"https://lowpaymentfee.com/api/v1/charges/185","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/charges/185","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.350","qualityRationale":"The x402 challenge is live and well-formed, confirming the endpoint works and pricing is clear ($0.02 USDC on Base). However, there is no documentation, no input/output schema, no examples, and the endpoint name 'Premium API Access' is generic and uninformative. The docs, pricing, and API pages all returned only a wallet-connect stub with no 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'/charges/185':197 '/request':16,32,157 '0.02':15,31,89,156 '000':80 '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913':69 '20':79 '402 payment required' '6':85 'Base USDC API' 'accept':64 'access':62,204 'actual':181 'advertis':112 'ai':9,25,124 'ai-inference' 'amount':74 'analysi':128 'analyt':8,24,118 'api':4,20,42,61,92,166,203 'base':7,23,51,71,81 'behavior':182 'behind':188 'broader':110 'call':41,77 'caller':237 'categori':114 'chain':108 'challeng':219 'classif':131 'classification' 'collect':36 'commit':98 'confirm':226 'connect':173 'content':178 'contract':68 'convers':148 'crawl':161 'data':117,121,186,212 'data-analytics' 'decim':86 'descript':207 'discov':241 'doc':164 'document':162,235 'embed':132 'embeddings' 'endpoint':13,29,43,55,116,152,190,196,228 'equal':88 'estim':142 'exchang':137 'experi':239 'export':122 'feed':136 'financ':10,26,133 'finance-data' 'form':225 'format':244 'four':113 'function':214 'gas':141 'gate':3,19,44 'generat':149 'generic':200 'geocod':146 'geocoding' 'howev':159 'individu':104 'infrastructur':144 'input/output':183 'insight':123 'key':93 'label':59 'lack':233 'learn':126 'limit':95 'list':151 'live':221 'low payment fee' 'lowpaymentfee.com':33 'machin':125 'maximum':73 'mean':236 'metric':119 'micropayment API' 'must':238 'need':100 'network':52 'offer':34 'on-chain':106 'on-chain API access' 'oper':230 'page':163 'pay':39 'pay-per-cal':38 'pay-per-call API' 'pay-per-request' 'payment':65 'per':40,76 'platform':111 'premium':60,202 'price':135,158,165 'prompt':174 'protocol':48 'quot':140 'rate':94,138 'refer':167 'remain':191 'report':120 'request':102 'requir':75 'respons':243 'return':168,216 'schema':184 'sentiment':127 'sentiment-analysis' 'settl':105 'share':153 'sourc':187 'specif':54,195 'substant':177 'suit':5,21 'summar':130 'text':129 'text-summarization' 'titl':199 'token':139 'unclear':210 'undocu':192 'unit':82 'upfront':97 'usd':90 'usdc':67,84 'usdc-base' 'util':12,28,145 'utility-apis' 'valid':147 'wallet':172 'wallet-connect':171 'web3':134 'well':224 'well-form':223 'without':205 'x402':2,18,47,218 'x402 API' 'x402-gated':1,17 'x402-payment'","prices":[{"id":"e3c9eec5-218a-4aaa-bd3a-f91f8af481d8","listingId":"1fd0e8c8-ceba-452d-b4f8-039f4da2ff80","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/charges/185","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:44:24.857Z"}],"sources":[{"listingId":"1fd0e8c8-ceba-452d-b4f8-039f4da2ff80","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/charges/185","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:44:24.857Z","lastSeenAt":"2026-04-23T01:01:21.969Z"}],"details":{"listingId":"1fd0e8c8-ceba-452d-b4f8-039f4da2ff80","quickStartSnippet":"# The endpoint returns HTTP 402 with an x402 challenge.\n# After constructing and signing the payment, include it in X-PAYMENT header:\ncurl -X POST https://lowpaymentfee.com/api/v1/charges/185 \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <signed-x402-payment-token>\"","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"The endpoint returns a 402 challenge requiring USDC payment on Base with maxAmountRequired of 20000 base units ($0.02)","source_url":"https://lowpaymentfee.com/api/v1/charges/185"},{"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 asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base","source_url":"https://lowpaymentfee.com/api/v1/charges/185"}],"useCases":["Paying per-request for AI inference (sentiment, summarization, classification, embeddings) without API keys","Fetching real-time financial data such as token quotes, gas estimates, and exchange rates","Running analytics queries and data exports on demand","Geocoding and data validation as utility microservices"],"bestFor":["Developers who want keyless, pay-as-you-go API access settled on Base","Agents and bots that can handle x402 payment flows natively","Low-volume or bursty workloads where subscription pricing is wasteful"],"notFor":["High-throughput production workloads needing SLAs and guaranteed uptime documentation","Users who need detailed API documentation and schema contracts before integrating","Anyone without a Base-compatible wallet or USDC balance"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:24.468Z"},"updatedAt":"2026-04-23T01:01:21.969Z"}}