{"id":"405a13d6-310f-483f-b9a2-e58a21057d23","shortId":"DtsRAa","kind":"x402","title":"Pay-per-call premium API access on Base via x402 — $0.02/request in USDC.","tagline":"Pay-per-call premium API access on Base via x402 — $0.02/request in USDC.","description":"This endpoint at lowpaymentfee.com provides \"Premium API Access\" via the x402 payment protocol. The site hosts a broad catalog of pay-per-request APIs spanning data & analytics, AI/ML inference (sentiment analysis, 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, payable in USDC on the Base network with no API keys, no rate limits, and no minimum commitments.\n\nThe specific endpoint `/api/v1/charges/291` is described simply as \"Premium API Access\" and returns a standard x402 challenge with a maxAmountRequired of 20,000 base units of USDC (0.02 USD, since USDC uses 6 decimals). Payment is sent to a specified Ethereum address on Base, and the endpoint accepts HTTP POST requests. The x402 version is 1, with a maximum timeout of 300 seconds.\n\nDocumentation is extremely sparse — the docs, API, pricing, and README pages all render only a \"Connect wallet\" prompt with no further content. There is no OpenAPI schema, no request/response examples, and no detailed description of what this particular charge endpoint returns. The landing page lists many API paths but provides no specifics on input parameters or output formats. Prospective users should be aware that the actual functionality behind this endpoint is unclear from available materials.","tags":[],"capabilities":["x402-payment","usdc-base","pay-per-request","http-post","no-api-key","no-rate-limit"],"categories":["api-gateway","misc"],"synonyms":["lowpaymentfee","low payment fee API","x402 API","pay-per-call API","USDC micropayment API","Base network API"],"warnings":["No documentation available — docs, API, pricing, and README pages all show only 'Connect wallet' with no content.","No OpenAPI or schema describing request parameters or response format for this endpoint.","The specific functionality of /api/v1/charges/291 ('Premium API Access') is undefined; it is unclear what data or service is returned after payment.","The site lists many API paths on its landing page but none have documented inputs or outputs."],"endpointUrl":"https://lowpaymentfee.com/api/v1/charges/291","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/291","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 documentation, no OpenAPI schema, no request/response examples, and the actual functionality behind 'Premium API Access' at /api/v1/charges/291 is completely undocumented. The site's docs pages are empty beyond a wallet-connect 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'/request':13,28 '0.02':12,27,88,136 '000':131 '1':164 '20':130 '300':170 '6':141 'Base network API' 'USDC micropayment API' 'accept':156 'access':7,22,38,119 'actual':237 'address':150 'ai/ml':59 'analysi':62 'analyt':58 'api':6,21,37,55,100,118,178,218 'avail':245 'awar':234 'base':9,24,96,132,152 'behind':239 'broad':48 'call':4,19 'catalog':49 'challeng':125 'charg':210 'classif':64 'commit':108 'connect':187 'content':193 'convers':81 'data':57 'decim':142 'describ':114 'descript':205 'detail':204 'doc':177 'document':172 'embed':65 'endpoint':32,84,111,155,211,241 'estim':75 'ethereum':149 'exampl':201 'exchang':70 'extrem':174 'feed':69 'financ':66 'format':229 'function':238 'gas':74 'generat':82 'geocod':79 'host':46 'http':157 'http-post' 'infer':60 'infrastructur':77 'input':225 'key':101 'land':214 'limit':104 'list':216 'low payment fee API' 'lowpaymentfee' 'lowpaymentfee.com':34 'mani':217 'materi':246 'maxamountrequir':128 'maximum':167 'minimum':107 'network':97 'no-api-key' 'no-rate-limit' 'openapi':197 'output':228 'page':182,215 'paramet':226 'particular':209 'path':219 'pay':2,17,52 'pay-per-cal':1,16 'pay-per-call API' 'pay-per-request':51 'payabl':91 'payment':42,143 'per':3,18,53,89 'post':158 'premium':5,20,36,117 'price':68,86,179 'prompt':189 'prospect':230 'protocol':43 'provid':35,221 'quot':73 'rate':71,103 'readm':181 'render':184 'request':54,90,159 'request/response':200 'return':121,212 'schema':198 'second':171 'sent':145 'sentiment':61 'simpli':115 'sinc':138 'site':45 'span':56 'spars':175 'specif':110,223 'specifi':148 'standard':123 'summar':63 'timeout':168 'token':72 'unclear':243 'unit':133 'usd':137 'usdc':15,30,93,135,139 'usdc-base' 'use':140 'user':231 'util':78 'valid':80 'version':162 'via':10,25,39 'wallet':188 'web3':67 'x402':11,26,41,124,161 'x402 API' 'x402-payment'","prices":[{"id":"8d6f348d-e419-4219-9af7-91bdeffb4db6","listingId":"405a13d6-310f-483f-b9a2-e58a21057d23","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/291","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:45:01.686Z"}],"sources":[{"listingId":"405a13d6-310f-483f-b9a2-e58a21057d23","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/charges/291","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:45:01.686Z","lastSeenAt":"2026-04-22T09:01:01.614Z"}],"details":{"listingId":"405a13d6-310f-483f-b9a2-e58a21057d23","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/charges/291 \\\n  -H \"Content-Type: application/json\"\n# Returns 402 with x402 payment challenge; attach X-PAYMENT header with signed USDC payment to access.","exampleRequest":null,"exampleResponse":{"error":"X-PAYMENT header is required","accepts":[{"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","extra":{"name":"USD Coin","version":"2"},"payTo":"0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3","scheme":"exact","network":"base","mimeType":"application/json","resource":"https://lowpaymentfee.com/api/v1/charges/291","description":"Premium API Access","maxAmountRequired":"20000","maxTimeoutSeconds":300}],"x402Version":1},"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/charges/291"},{"claim":"All endpoints 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":"Docs, API, pricing, and README pages render only a 'Connect wallet' prompt","source_url":"https://lowpaymentfee.com/docs"}],"useCases":["Accessing premium API functionality with per-request USDC micropayments on Base","Agent-driven API consumption without pre-registration or API keys","Programmatic pay-as-you-go access to data, AI, finance, or utility endpoints"],"bestFor":["Developers wanting zero-commitment, keyless API access","AI agents that can settle x402 payments autonomously on Base","Users who prefer crypto micropayments over subscription billing"],"notFor":["Users needing detailed API documentation or guaranteed SLAs before purchasing","Applications requiring high-throughput bulk access at volume-discounted rates","Users without a Base-compatible USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:22.711Z"},"updatedAt":"2026-04-22T09:01:01.614Z"}}