{"id":"3a208566-2037-4623-b704-60838cfcfc71","shortId":"AnmehS","kind":"x402","title":"x402-gated premium API access on Base, pay $0.02 per request in USDC — no API keys required.","tagline":"x402-gated premium API access on Base, pay $0.02 per request in USDC — no API keys required.","description":"This endpoint at lowpaymentfee.com provides \"Premium API Access\" via the x402 payment protocol on the Base network. The site hosts a broad catalog of pay-per-call APIs spanning data & analytics, 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, settled in USDC on Base.\n\nThe specific endpoint `/api/v1/charges/172` is labeled \"Premium API Access\" and returns a standard x402 challenge with a maxAmountRequired of 20,000 base units of USDC (0x8335…2913 on Base, 6 decimals), which equals $0.02. Payment is made via the x402 exact scheme — callers attach an X-PAYMENT header with a signed payment to the payTo address. There are no API keys, no rate limits, and no subscription commitments; access is instant once payment is included.\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, and no explanation of what data or functionality the `/api/v1/charges/172` endpoint actually returns. The endpoint is confirmed live (402 challenge captured), but without documentation it is unclear what input the POST body should contain or what the response payload looks like.","tags":[],"capabilities":["x402-payment","usdc-settlement","base-network","pay-per-request","no-api-key","post-method","json-response"],"categories":["api-gateway","pay-per-call"],"synonyms":["low payment fee API","x402 API","USDC pay-per-call","Base network API","micropayment API","premium API access","crypto-paid API"],"warnings":["No documentation available — /docs, /api, /pricing, and /README all return only a 'Connect wallet' prompt with no technical content.","No OpenAPI or schema describing request parameters or response format for this endpoint.","The specific functionality of /api/v1/charges/172 ('Premium API Access') is not explained anywhere; it may be a generic charge endpoint rather than a distinct service.","Cannot verify what data or service is actually delivered upon successful payment."],"endpointUrl":"https://lowpaymentfee.com/api/v1/charges/172","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/172","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.300","qualityRationale":"The endpoint is confirmed live via a valid x402 402 challenge, and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond a wallet-connect prompt, and the specific purpose of /api/v1/charges/172 is undefined. This is effectively a stub 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'/api/v1/charges/172':111,224 '/docs':189 '/pricing':191 '/readme':193 '0.02':10,28,100,141 '000':128 '0x8335':133 '20':127 '2913':134 '402':233 '6':137 'Base network API' 'USDC pay-per-call' 'access':6,24,44,116,177 'actual':226 'address':164 'ai':69 'analysi':73 'analyt':68 'api':5,16,23,34,43,65,115,168 'attach':151 'base':8,26,52,107,129,136 'base-network' 'bodi':246 'broad':58 'call':64 'caller':150 'captur':235 'catalog':59 'challeng':122,234 'classif':76 'commit':176 'confirm':231 'connect':199 'contain':248 'convers':93 'crypto-paid API' 'data':67,220 'decim':138 'detail':206 'document':184,238 'embed':77 'endpoint':38,96,110,225,229 'equal':140 'estim':87 'exact':148 'exchang':82 'explan':217 'extrem':186 'feed':81 'financ':78 'function':222 'gas':86 'gate':3,21 'generat':94 'geocod':91 'header':156 'host':56 'includ':183 'infrastructur':89 'input':243 'instant':179 'json-response' 'key':17,35,169 'label':113 'learn':71 'like':255 'limit':172 'live':232 'look':254 'low payment fee API' 'lowpaymentfee.com':40 'machin':70 'made':144 'maxamountrequir':125 'micropayment API' 'network':53 'no-api-key' 'openapi':210 'page':194 'pay':9,27,62 'pay-per-cal':61 'pay-per-request' 'payload':253 'payment':48,142,155,160,181 'payto':163 'per':11,29,63,101 'post':245 'post-method' 'premium':4,22,42,114 'premium API access' 'price':80,98 'prompt':201 'protocol':49 'provid':41 'quot':85 'rate':83,171 'render':196 'request':12,30,102 'request/response':213 'requir':18,36 'respons':252 'return':118,227 'schema':214 'scheme':149 'sentiment':72 'settl':103 'sign':159 'site':55 'span':66 'spars':187 'spec':211 'specif':109 'standard':120 'subscript':175 'summar':75 'technic':205 'text':74 'token':84 'unclear':241 'unit':130 'usdc':14,32,105,132 'usdc-settlement' 'util':90 'valid':92 'via':45,145 'wallet':200 'web3':79 'without':237 'x':154 'x-payment':153 'x402':2,20,47,121,147 'x402 API' 'x402-gated':1,19 'x402-payment'","prices":[{"id":"c4ed0b05-eca1-467b-951e-a2190de4da9e","listingId":"3a208566-2037-4623-b704-60838cfcfc71","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/172","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:44:21.812Z"}],"sources":[{"listingId":"3a208566-2037-4623-b704-60838cfcfc71","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/charges/172","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:44:21.812Z","lastSeenAt":"2026-04-24T05:02:31.313Z"}],"details":{"listingId":"3a208566-2037-4623-b704-60838cfcfc71","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/charges/172 \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <signed-x402-payment-header>\" \\\n  -d '{}'","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/charges/172"},{"claim":"All APIs are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base network","source_url":"https://lowpaymentfee.com"},{"claim":"The site offers APIs across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categories","source_url":"https://lowpaymentfee.com"},{"claim":"USDC contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 with 6 decimals","source_url":"https://lowpaymentfee.com/api/v1/charges/172"}],"useCases":["Programmatic access to paid API endpoints without managing API keys or subscriptions","Agent-driven workflows that need to pay per call using on-chain USDC on Base","Exploring a catalog of data, AI, finance, and utility APIs with uniform $0.02 pricing"],"bestFor":["Developers or agents wanting frictionless pay-per-call API access via x402","Users who prefer crypto micropayments over traditional subscription billing","Quick prototyping against multiple API categories without signup"],"notFor":["Users who need detailed API documentation or OpenAPI specs before integrating","High-volume production workloads where per-request crypto settlement adds latency","Users without a Base-compatible wallet or USDC holdings"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:24.604Z"},"updatedAt":"2026-04-24T05:02:31.313Z"}}