{"id":"13f1807e-b5b0-42bd-b975-347cb95b9fdf","shortId":"4PCmae","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 specific resource `/api/v1/messages/198` accepts POST requests and charges up to 20,000 base units of USDC on the Base network per call, which translates to $0.02 per request (USDC uses 6 decimals). Payment is handled inline via the x402 header — no API keys, accounts, or rate limits are required.\n\nThe broader lowpaymentfee.com platform advertises a suite of pay-per-call APIs 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 endpoints are listed at $0.02 per request and settle in USDC on the Base L2 network.\n\nHowever, the specific endpoint being listed here (`/api/v1/messages/198`) does not clearly map to any of the documented API categories. Its description is simply \"Premium API Access\" with no further documentation on input/output schemas, expected request body format, or what data it returns. The site's docs, pricing, and README pages all resolve to a minimal \"Connect wallet\" prompt with no additional technical detail. Treat this endpoint with caution: it is live and responds with a valid x402 challenge, but its actual functionality is undocumented.","tags":[],"capabilities":["x402-payment","usdc-base","pay-per-call","no-api-key","post-endpoint"],"categories":["api-gateway","misc"],"synonyms":["x402 API","pay per request API","USDC micropayment API","Base network API","lowpaymentfee","402 payment endpoint","crypto API access"],"warnings":["The specific endpoint /api/v1/messages/198 does not match any of the documented API categories on the site — its purpose is unknown.","No input or output schema is documented; the request body format is entirely unknown.","The site's /pricing, /README, and /api pages all render only a 'Connect wallet' prompt with no technical content.","Without knowing what this endpoint returns, callers risk paying $0.02 per call for an unknown response."],"endpointUrl":"https://lowpaymentfee.com/api/v1/messages/198","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/messages/198","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.250","qualityRationale":"The endpoint is live and returns a valid x402 402 challenge, but there is zero documentation on what the /api/v1/messages/198 resource actually does, what request body it expects, or what it returns. No OpenAPI spec, no examples, and the site's docs pages are empty. This is effectively a stub 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'/request':13,28 '0.02':12,27,70,148 '000':56 '20':55 '402 payment endpoint' '6':75 'Base network API' 'USDC micropayment API' 'accept':48 'access':7,22,38,185 'account':88 'across':107 'actual':240 'addit':220 'advertis':98 'ai':117 'analysi':121 'analyt':111 'api':6,21,37,86,106,177,184 'base':9,24,57,63,157 'bodi':195 'broader':95 'call':4,19,66,105 'categori':109,178 'caution':227 'challeng':237 'charg':52 'classif':124 'clear':170 'connect':215 'convers':141 'crypto API access' 'data':110,114,199 'decim':76 'descript':180 'detail':222 'doc':205 'document':176,189 'embed':125 'endpoint':32,144,163,225 'estim':135 'exchang':130 'expect':193 'export':115 'feed':129 'financ':126 'format':196 'four':108 'function':241 'gas':134 'generat':142 'geocod':139 'handl':79 'header':84 'howev':160 'infrastructur':137 'inlin':80 'input/output':191 'insight':116 'key':87 'l2':158 'learn':119 'limit':91 'list':146,165 'live':230 'lowpaymentfee' 'lowpaymentfee.com':34,96 'machin':118 'map':171 'metric':112 'minim':214 'network':64,159 'no-api-key' 'page':209 'pay':2,17,103 'pay per request API' 'pay-per-cal':1,16,102 'pay-per-call' 'payment':42,77 'per':3,18,65,71,104,149 'platform':97 'post':49 'post-endpoint' 'premium':5,20,36,183 'price':128,206 'prompt':217 'protocol':43 'provid':35 'quot':133 'rate':90,131 'readm':208 'report':113 'request':50,72,150,194 'requir':93 'resolv':211 'resourc':46 'respond':232 'return':201 'schema':192 'sentiment':120 'settl':152 'simpli':182 'site':203 'specif':45,162 'suit':100 'summar':123 'technic':221 'text':122 'token':132 'translat':68 'treat':223 'undocu':243 'unit':58 'usdc':15,30,60,73,154 'usdc-base' 'use':74 'util':138 'valid':140,235 'via':10,25,39,81 'wallet':216 'web3':127 'x402':11,26,41,83,236 'x402 API' 'x402-payment'","prices":[{"id":"9081ec98-039a-431e-ba5b-a1a053b8da00","listingId":"13f1807e-b5b0-42bd-b975-347cb95b9fdf","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/messages/198","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-21T18:32:26.805Z"}],"sources":[{"listingId":"13f1807e-b5b0-42bd-b975-347cb95b9fdf","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/messages/198","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:26.805Z","lastSeenAt":"2026-04-22T02:32:07.803Z"}],"details":{"listingId":"13f1807e-b5b0-42bd-b975-347cb95b9fdf","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/messages/198 \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <x402-payment-token>\" \\\n  -d '{}'","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Base network","source_url":"https://lowpaymentfee.com/api/v1/messages/198"},{"claim":"USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","source_url":"https://lowpaymentfee.com/api/v1/messages/198"},{"claim":"All listed APIs 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 platform offers APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories","source_url":"https://lowpaymentfee.com"}],"useCases":["Programmatic access to a premium API resource without needing an API key or account","Agent-driven workflows that can settle per-call payments in USDC on Base","Testing x402 payment protocol integrations against a live endpoint"],"bestFor":["Developers experimenting with x402 payment flows","AI agents that can autonomously pay for API calls via crypto","Users who want pay-as-you-go access without subscriptions"],"notFor":["Anyone needing documented input/output schemas before integrating","Production workloads requiring SLA guarantees or support","Users without USDC on the Base network"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:00.437Z"},"updatedAt":"2026-04-22T02:32:07.803Z"}}