{"id":"3e9c5695-10f6-4a7c-82a1-34de311f2886","shortId":"RxpCKT","kind":"x402","title":"Premium API access key via x402 micropayment on Base network, paid in USDC.","tagline":"Premium API access key via x402 micropayment on Base network, paid in USDC.","description":"This endpoint at lowpaymentfee.com provides a \"Premium API Access\" resource at `/api/v1/apikeys/50`, payable per-call via the x402 protocol on the Base network using USDC. The x402 challenge is live and returns a 402 with a maximum required amount of 20,000 base units of USDC (0.02 USD per request). The site advertises a broad catalog of pay-per-request APIs spanning data & analytics, AI & machine learning (sentiment analysis, summarization, classification, embeddings), finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation) — all at $0.02 per call with no API keys, no rate limits, and instant access.\n\nThis specific endpoint (`/api/v1/apikeys/50`) appears to be an API key provisioning or access endpoint rather than one of the data/AI/finance endpoints listed on the homepage. The exact payload it expects and the response it returns are not documented in the crawled material — the docs, API, pricing, and README pages all rendered only a \"Connect wallet\" prompt with no further content. Without an OpenAPI schema or example request/response documentation, the precise input format and output structure remain unknown. Users should expect to POST to this endpoint with an x402 payment header and receive a JSON response, but specifics must be discovered experimentally.","tags":[],"capabilities":["x402-payment","usdc-base-network","api-key-provisioning","pay-per-request","no-api-key-required","micropayment"],"categories":["infrastructure","api-access"],"synonyms":["premium API key","x402 API access","USDC micropayment API","Base network API","pay-per-call API","lowpaymentfee"],"warnings":["No OpenAPI or schema documentation available — request/response format is unknown","Docs, API, pricing, and README pages all render only 'Connect wallet' with no usable content","The exact purpose of /api/v1/apikeys/50 (vs. the listed data/AI/finance endpoints) is not documented","Cannot verify what the endpoint actually returns upon successful payment"],"endpointUrl":"https://lowpaymentfee.com/api/v1/apikeys/50","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/apikeys/50","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 pricing is clear ($0.02 USDC on Base), but there is no OpenAPI schema, no documented request/response format, and all docs pages render only a wallet-connect prompt. The purpose of this specific endpoint (apikeys/50) versus the broader catalog is 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'0.02':74,120 '000':69 '20':68 '402':61 'Base network API' 'USDC micropayment API' 'access':3,16,35,132,145 'advertis':80 'ai':93 'amount':66 'analysi':97 'analyt':92 'api':2,15,34,89,125,141,177 'api-key-provisioning' 'appear':137 'base':9,22,49,70 'broad':82 'call':42,122 'catalog':83 'challeng':55 'classif':99 'connect':186 'content':192 'convers':116 'crawl':173 'data':91 'data/ai/finance':152 'discov':232 'doc':176 'document':170,200 'embed':100 'endpoint':28,135,146,153,217 'estim':110 'exact':159 'exampl':198 'exchang':105 'expect':162,212 'experiment':233 'feed':104 'financ':101 'format':204 'gas':109 'generat':117 'geocod':114 'header':222 'homepag':157 'infrastructur':112 'input':203 'instant':131 'json':226 'key':4,17,126,142 'learn':95 'limit':129 'list':154 'live':57 'lowpaymentfee' 'lowpaymentfee.com':30 'machin':94 'materi':174 'maximum':64 'micropay':7,20 'micropayment' 'must':230 'network':10,23,50 'no-api-key-required' 'one':149 'openapi':195 'output':206 'page':181 'paid':11,24 'pay':86 'pay-per-call API' 'pay-per-request':85 'payabl':39 'payload':160 'payment':221 'per':41,76,87,121 'per-cal':40 'post':214 'precis':202 'premium':1,14,33 'premium API key' 'price':103,178 'prompt':188 'protocol':46 'provid':31 'provis':143 'quot':108 'rate':106,128 'rather':147 'readm':180 'receiv':224 'remain':208 'render':183 'request':77,88 'request/response':199 'requir':65 'resourc':36 'respons':165,227 'return':59,167 'schema':196 'sentiment':96 'site':79 'span':90 'specif':134,229 'structur':207 'summar':98 'token':107 'unit':71 'unknown':209 'usd':75 'usdc':13,26,52,73 'usdc-base-network' 'use':51 'user':210 'util':113 'valid':115 'via':5,18,43 'wallet':187 'web3':102 'without':193 'x402':6,19,45,54,220 'x402 API access' 'x402-payment'","prices":[{"id":"b0543336-f6b0-464b-a707-f1bf72c3138a","listingId":"3e9c5695-10f6-4a7c-82a1-34de311f2886","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/apikeys/50","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T19:29:32.571Z"}],"sources":[{"listingId":"3e9c5695-10f6-4a7c-82a1-34de311f2886","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/apikeys/50","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T19:29:32.571Z","lastSeenAt":"2026-04-23T06:31:45.963Z"}],"details":{"listingId":"3e9c5695-10f6-4a7c-82a1-34de311f2886","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/apikeys/50 \\\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 of USDC (0.02 USD) on Base network","source_url":"https://lowpaymentfee.com/api/v1/apikeys/50"},{"claim":"The site advertises APIs across data & analytics, AI & ML, finance & Web3, and infrastructure at $0.02 per request","source_url":"https://lowpaymentfee.com"},{"claim":"Pricing is $0.02/request with no API keys, no rate limits, and instant access","source_url":"https://lowpaymentfee.com"},{"claim":"USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base network","source_url":"https://lowpaymentfee.com/api/v1/apikeys/50"}],"useCases":["Acquiring a premium API key for accessing lowpaymentfee.com services","Programmatic provisioning of API credentials via micropayment","Agent-driven on-demand API access without pre-registration"],"bestFor":["Agents needing instant API access without signup or subscription","Developers who want pay-per-use API key provisioning on Base/USDC","Automated workflows requiring frictionless credential acquisition"],"notFor":["Users needing detailed API documentation before purchasing","High-volume consumers who prefer subscription-based pricing"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:29.054Z"},"updatedAt":"2026-04-23T06:31:45.963Z"}}