{"id":"8f38f792-4bb8-45ec-9c22-9f8f01e9dd15","shortId":"jrt7Sg","kind":"x402","title":"Pay-per-request API collection on Base via x402 — $0.02/call in USDC, no API keys required.","tagline":"Pay-per-request API collection on Base via x402 — $0.02/call in USDC, no API keys required.","description":"lowpaymentfee.com hosts a collection of pay-per-request APIs accessible via the x402 payment protocol on the Base network. The endpoint at `/api/v1/collections/39` is labeled \"Premium API Access\" and accepts POST requests with an x402 payment header. Payment is settled in USDC (contract 0x8335…2913 on Base) at a maximum cost of $0.02 per request (20,000 base units with 6 decimals). No API keys, rate limits, or upfront commitments are required — each call is individually paid.\n\nThe broader platform advertises endpoints across four categories: 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 specific endpoint `/api/v1/collections/39` does not clearly map to any single one of these categories — it may serve as an aggregated collection endpoint or a gateway to the broader API suite.\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 x402 challenge confirms the endpoint is live and accepting payment-gated POST requests, but what data or functionality it actually returns is unknown from the available sources.","tags":[],"capabilities":["x402-payment","usdc-settlement","base-network","pay-per-request","no-api-key","post-endpoint"],"categories":["api-gateway","data"],"synonyms":["x402 API","pay per call API","USDC API","Base network API","micropayment API","lowpaymentfee","crypto-paid API"],"warnings":["No OpenAPI or schema documentation available — request and response formats are entirely unknown","All documentation pages (docs, API, pricing, README) return only a 'Connect wallet' prompt with no content","The specific purpose of /api/v1/collections/39 ('Premium API Access') is unclear — it may differ from the individually listed endpoints","No examples or error handling documentation found"],"endpointUrl":"https://lowpaymentfee.com/api/v1/collections/39","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/collections/39","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.300","qualityRationale":"The x402 challenge confirms the endpoint is live with clear pricing ($0.02 USDC on Base), but there is zero documentation on request/response schemas, no OpenAPI spec, and all doc pages render only a wallet-connect prompt. The actual functionality behind this specific endpoint is 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'/call':12,30 '/request':163 '0.02':11,29,90,162 '000':94 '0x8335':81 '20':93 '2913':82 '6':98 'Base network API' 'USDC API' 'accept':67,247 'access':47,65 'across':120 'actual':259 'advertis':118 'aggreg':186 'ai':130 'analysi':134 'analyt':124 'api':5,16,23,34,46,64,101,195,203 'avail':233,265 'base':8,26,55,84,95 'base-network' 'broader':116,194 'call':111 'categori':122,180 'challeng':240 'classif':137 'clear':172 'collect':6,24,40,187 'commit':107 'confirm':241 'connect':212 'contract':80 'convers':154 'cost':88 'crawl':236 'crypto-paid API' 'data':123,127,255 'decim':99 'detail':219 'doc':202 'document':197,228 'embed':138 'endpoint':58,119,158,168,188,243 'estim':148 'exampl':232 'exchang':143 'export':128 'extrem':199 'feed':142 'financ':139 'four':121 'function':257 'gas':147 'gate':250 'gateway':191 'generat':155 'geocod':152 'header':74 'host':38 'howev':165 'individu':113 'infrastructur':150 'insight':129 'key':17,35,102 'label':62 'learn':132 'limit':104 'list':157 'live':245 'lowpaymentfee' 'lowpaymentfee.com':37 'machin':131 'map':173 'materi':237 'maximum':87 'may':182 'metric':125 'micropayment API' 'network':56 'no-api-key' 'one':177 'openapi':223 'page':207 'paid':114 'pay':2,20,43 'pay per call API' 'pay-per-request':1,19,42 'payment':51,73,75,249 'payment-g':248 'per':3,21,44,91 'platform':117 'post':68,251 'post-endpoint' 'premium':63 'price':141,164,204 'prompt':214 'protocol':52 'quot':146 'rate':103,144 'readm':206 'render':209 'report':126 'request':4,22,45,69,92,252 'request/response':226 'requir':18,36,109 'return':260 'schema':227 'sentiment':133 'serv':183 'settl':77 'share':159 'singl':176 'sourc':266 'spars':200 'spec':224 'specif':167 'suit':196 'summar':136 'technic':218 'text':135 'token':145 'unit':96 'unknown':262 'upfront':106 'usag':231 'usdc':14,32,79 'usdc-settlement' 'util':151 'valid':153 'via':9,27,48 'wallet':213 'web3':140 'x402':10,28,50,72,239 'x402 API' 'x402-payment'","prices":[{"id":"401010b1-4c7d-439c-b6f8-123acad2c408","listingId":"8f38f792-4bb8-45ec-9c22-9f8f01e9dd15","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/collections/39","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-19T05:29:46.993Z"}],"sources":[{"listingId":"8f38f792-4bb8-45ec-9c22-9f8f01e9dd15","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/collections/39","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-19T05:29:46.993Z","lastSeenAt":"2026-04-22T04:02:20.914Z"}],"details":{"listingId":"8f38f792-4bb8-45ec-9c22-9f8f01e9dd15","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/collections/39 \\\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":"Endpoint returns 402 with x402 challenge accepting USDC on Base at maxAmountRequired 20000","source_url":"https://lowpaymentfee.com/api/v1/collections/39"},{"claim":"Platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access","source_url":"https://lowpaymentfee.com"},{"claim":"USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","source_url":"https://lowpaymentfee.com/api/v1/collections/39"},{"claim":"API categories include Data & Analytics, AI & ML, Finance & Web3, and Infrastructure","source_url":"https://lowpaymentfee.com"}],"useCases":["Accessing pay-per-request data or AI endpoints without needing API key registration","Making USDC micropayments on Base for individual API calls","Integrating x402-compatible agents with a low-cost API collection"],"bestFor":["Developers or agents wanting zero-signup, pay-as-you-go API access","x402-compatible wallets and autonomous agents on Base","Low-volume or experimental usage where per-call pricing is preferred over subscriptions"],"notFor":["Users who need detailed API documentation or guaranteed SLAs before integrating","High-volume production workloads where per-call costs add up quickly","Users without a Base-compatible USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:24.76Z"},"updatedAt":"2026-04-22T04:02:20.914Z"}}