{"id":"ec9036d8-c1cc-4cba-b7d8-51ed05a955f6","shortId":"XU2PR6","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":"lowpaymentfee.com hosts a collection of pay-per-request API endpoints accessible via the x402 payment protocol on the Base network. The specific endpoint at `/api/v1/payments/333` is labeled \"Premium API Access\" and requires a per-call payment of up to 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 per request (USDC uses 6 decimals). Payment is settled on-chain with no API keys, no rate limits, and no upfront commitments.\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, this specific listing covers only the `/api/v1/payments/333` endpoint, whose exact functionality beyond \"Premium API Access\" is not documented in detail.\n\nThe endpoint is live and returns a valid x402 challenge (HTTP 402) with scheme \"exact\" on the Base network. The payment timeout is 300 seconds. Documentation pages (/docs, /pricing, /api, /README) all resolve but contain only a \"Connect wallet\" prompt with no further technical detail, so the actual request/response schema for this endpoint is unknown.","tags":[],"capabilities":["x402-payment","per-request-billing","usdc-base","no-api-key","pay-per-use"],"categories":["api-gateway","payments"],"synonyms":["x402 API","micropayment API","pay-per-call","USDC API access","Base network API","low fee API","crypto-paid endpoint"],"warnings":["No documentation available — /docs, /pricing, /api, and /README pages all show only 'Connect wallet' with no content","The actual response payload after successful payment is completely unknown","No OpenAPI spec or request/response schema provided","Endpoint name 'Premium API Access' is generic and does not describe what data or service is returned"],"endpointUrl":"https://lowpaymentfee.com/api/v1/payments/333","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/payments/333","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.400","qualityRationale":"The endpoint is live and returns a valid x402 challenge with clear pricing ($0.02 USDC on Base). However, there is no documentation of what the endpoint actually returns after payment, no request/response schema, and all doc pages are empty stubs showing only 'Connect wallet'. The exact functionality behind 'Premium API Access' is 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'/api/v1/payments/333':56,165 '/docs':206 '/pricing':207 '/readme':209 '/request':13,28,156 '0.02':12,27,84,155 '000':73 '0x8335':78 '20':72 '2913':79 '300':202 '402':190 '6':89 'Base network API' 'USDC API access' 'access':7,22,42,61,173 'across':113 'actual':226 'advertis':111 'ai':123 'analysi':127 'analyt':117 'api':6,21,40,60,99,172 'base':9,24,50,74,81,196 'beyond':170 'broader':109 'call':4,19,67 'categori':115 'chain':96 'challeng':188 'classif':130 'collect':34 'commit':107 'connect':216 'contain':213 'convers':147 'cover':162 'crypto-paid endpoint' 'data':116,120 'decim':90 'detail':178,223 'document':176,204 'embed':131 'endpoint':41,54,112,151,166,180,231 'equal':83 'estim':141 'exact':168,193 'exchang':136 'export':121 'feed':135 'financ':132 'four':114 'function':169 'gas':140 'generat':148 'geocod':145 'host':32 'howev':158 'http':189 'infrastructur':143 'insight':122 'key':100 'label':58 'learn':125 'limit':103 'list':150,161 'live':182 'low fee API' 'lowpaymentfee.com':31 'machin':124 'metric':118 'micropayment API' 'network':51,197 'no-api-key' 'on-chain':94 'page':205 'pay':2,17,37 'pay-per-cal':1,16 'pay-per-call' 'pay-per-request':36 'pay-per-use' 'payment':46,68,91,199 'per':3,18,38,66,85 'per-cal':65 'per-request-billing' 'platform':110 'premium':5,20,59,171 'price':134,157 'prompt':218 'protocol':47 'quot':139 'rate':102,137 'report':119 'request':39,86 'request/response':227 'requir':63 'resolv':211 'return':184 'schema':228 'scheme':192 'second':203 'sentiment':126 'settl':93 'share':152 'specif':53,160 'summar':129 'technic':222 'text':128 'timeout':200 'token':138 'unit':75 'unknown':233 'upfront':106 'usdc':15,30,77,87 'usdc-base' 'use':88 'util':144 'valid':146,186 'via':10,25,43 'wallet':217 'web3':133 'whose':167 'x402':11,26,45,187 'x402 API' 'x402-payment'","prices":[{"id":"1034fbb8-1216-45dc-a5cd-9bcb3128e82b","listingId":"ec9036d8-c1cc-4cba-b7d8-51ed05a955f6","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/payments/333","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:50:33.206Z"}],"sources":[{"listingId":"ec9036d8-c1cc-4cba-b7d8-51ed05a955f6","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/payments/333","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:50:33.206Z","lastSeenAt":"2026-04-23T11:03:35.190Z"}],"details":{"listingId":"ec9036d8-c1cc-4cba-b7d8-51ed05a955f6","quickStartSnippet":"# The endpoint returns HTTP 402 with an x402 challenge.\n# Use an x402-compatible client to pay and access:\ncurl -X POST https://lowpaymentfee.com/api/v1/payments/333 \\\n  -H 'Content-Type: application/json'\n# Response: 402 with X-Payment challenge. Supply X-PAYMENT header with signed USDC payment on Base.","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/payments/333","description":"Premium API Access","maxAmountRequired":"20000","maxTimeoutSeconds":300}],"x402Version":1},"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"Endpoint returns a valid x402 challenge with maxAmountRequired of 20000 USDC base units on Base network","source_url":"https://lowpaymentfee.com/api/v1/payments/333"},{"claim":"All endpoints priced at $0.02/request with no API keys, no rate limits, and instant access on Base network","source_url":"https://lowpaymentfee.com"},{"claim":"USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","source_url":"https://lowpaymentfee.com/api/v1/payments/333"},{"claim":"Platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories","source_url":"https://lowpaymentfee.com"}],"useCases":["Agents that need on-demand API access without pre-registration or API keys","Programmatic pay-per-call access to premium data or services settled in USDC on Base","Testing x402 protocol integrations with a low-cost live endpoint"],"bestFor":["Developers or agents wanting keyless, pay-as-you-go API access","x402 protocol experimentation at very low cost ($0.02/call)","On-chain settled API consumption without subscriptions"],"notFor":["Users who need detailed API documentation or guaranteed SLAs","High-volume use cases where per-request crypto settlement overhead matters","Anyone without a Base-compatible USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:06.73Z"},"updatedAt":"2026-04-23T11:03:35.190Z"}}