{"id":"9ba3fd92-82ed-46b5-8a0e-90bbaea10cc0","shortId":"q24sZc","kind":"x402","title":"Premium API access via x402 micropayment on Base — $0.02 per request in USDC.","tagline":"Premium API access via x402 micropayment on Base — $0.02 per request in USDC.","description":"This endpoint at lowpaymentfee.com provides \"Premium API Access\" gated behind the x402 payment protocol. The site hosts a broad catalog of pay-per-call APIs spanning 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 endpoints are priced at $0.02 per request, settled in USDC on the Base network.\n\nThe specific endpoint `/api/v1/apikeys/25` is described only as \"Premium API Access\" and returns a live x402 402 challenge with a maxAmountRequired of 20,000 base units of USDC (0x8335…2913 on Base), 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 signup required; 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 content. There is no OpenAPI spec, no request/response schema, and no examples available. The purpose of the `/api/v1/apikeys/25` path specifically (as opposed to the other listed endpoints) is unclear — it may generate or retrieve an API key, but this is unconfirmed. Prospective callers should be aware that without documented input/output schemas, integration requires experimentation.","tags":[],"capabilities":["x402-payment","usdc-base","pay-per-request","api-key-generation","micropayment"],"categories":["infrastructure","api-access"],"synonyms":["premium API","x402 API key","USDC micropayment API","Base network API","pay-per-call API","lowpaymentfee"],"warnings":["No OpenAPI or schema documentation available — all docs pages render only 'Connect wallet'","The specific function of /api/v1/apikeys/25 is undocumented; 'Premium API Access' is vague","No request body schema or response schema is provided; integration requires trial and error","The site lists many other endpoints but none have documented schemas either"],"endpointUrl":"https://lowpaymentfee.com/api/v1/apikeys/25","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/25","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.300","qualityRationale":"The endpoint is live and returns a valid x402 402 challenge, confirming it is operational. However, there is no OpenAPI spec, no documented request/response schema, no examples, and the docs pages are empty. The specific purpose of /api/v1/apikeys/25 is unclear beyond the generic 'Premium API Access' 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'/api/v1/apikeys/25':105,217 '/docs':184 '/pricing':186 '/readme':188 '0.02':9,22,92,136 '000':125 '0x8335':130 '20':124 '2913':131 '402':118 'Base network API' 'USDC micropayment API' 'access':3,16,34,112,172 'address':159 'ai':61 'analysi':65 'analyt':55 'api':2,15,33,52,111,163,235 'api-key-generation' 'attach':146 'avail':212 'awar':245 'base':8,21,100,126,133 'behind':36 'broad':45 'call':51 'caller':145,242 'catalog':46 'challeng':119 'classif':68 'connect':194 'content':200 'convers':85 'data':54,58 'describ':107 'document':179,248 'embed':69 'endpoint':28,88,104,226 'equal':135 'estim':79 'exact':143 'exampl':211 'exchang':74 'experiment':253 'export':59 'extrem':181 'feed':73 'financ':70 'gas':78 'gate':35 'generat':86,231 'geocod':83 'header':151 'host':43 'includ':178 'infrastructur':81 'input/output':249 'insight':60 'instant':174 'integr':251 'key':164,236 'learn':63 'limit':167 'list':225 'live':116 'lowpaymentfee' 'lowpaymentfee.com':30 'machin':62 'made':139 'maxamountrequir':122 'may':230 'metric':56 'micropay':6,19 'micropayment' 'network':101 'openapi':204 'oppos':221 'page':189 'path':218 'pay':49 'pay-per-cal':48 'pay-per-call API' 'pay-per-request' 'payment':39,137,150,155,176 'payto':158 'per':10,23,50,93 'premium':1,14,32,110 'premium API' 'price':72,90 'prompt':196 'prospect':241 'protocol':40 'provid':31 'purpos':214 'quot':77 'rate':75,166 'render':191 'report':57 'request':11,24,94 'request/response':207 'requir':171,252 'retriev':233 'return':114 'schema':208,250 'scheme':144 'sentiment':64 'settl':95 'sign':154 'signup':170 'site':42 'span':53 'spars':182 'spec':205 'specif':103,219 'summar':67 'text':66 'token':76 'unclear':228 'unconfirm':240 'unit':127 'usdc':13,26,97,129 'usdc-base' 'util':82 'valid':84 'via':4,17,140 'wallet':195 'web3':71 'without':247 'x':149 'x-payment':148 'x402':5,18,38,117,142 'x402 API key' 'x402-payment'","prices":[{"id":"3a4cd70a-b5a3-45cd-b3e1-1ca5eae4d37f","listingId":"9ba3fd92-82ed-46b5-8a0e-90bbaea10cc0","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/25","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T19:29:21.671Z"}],"sources":[{"listingId":"9ba3fd92-82ed-46b5-8a0e-90bbaea10cc0","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/apikeys/25","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T19:29:21.671Z","lastSeenAt":"2026-04-23T09:31:52.680Z"}],"details":{"listingId":"9ba3fd92-82ed-46b5-8a0e-90bbaea10cc0","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/apikeys/25 \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <x402-signed-payment>\"","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"The endpoint returns a live x402 402 challenge with maxAmountRequired of 20000 base units of USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/apikeys/25"},{"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 USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","source_url":"https://lowpaymentfee.com/api/v1/apikeys/25"},{"claim":"Docs, API, pricing, and README pages render only a 'Connect wallet' prompt","source_url":"https://lowpaymentfee.com/docs"}],"useCases":["Acquiring API keys or premium access tokens via a single micropayment","Programmatic agents purchasing API credentials without signup or subscription","Demonstrating x402 payment-gated API access on Base"],"bestFor":["Agents or developers wanting instant, keyless API access via crypto micropayment","x402-compatible wallets and agent frameworks on Base","Low-friction pay-per-use API consumption without accounts"],"notFor":["Users who need detailed API documentation or OpenAPI specs before integrating","High-volume consumers who prefer subscription-based pricing over per-call payments","Non-crypto users without a Base-compatible wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:29.494Z"},"updatedAt":"2026-04-23T09:31:52.680Z"}}