{"id":"0870f947-edb7-4712-91b4-d4768e3222c0","shortId":"8NFNtw","kind":"x402","title":"Pay-per-call API platform on Base (USDC) covering data, AI, finance, and utility endpoints at $0.02/request.","tagline":"Pay-per-call API platform on Base (USDC) covering data, AI, finance, and utility endpoints at $0.02/request.","description":"lowpaymentfee.com is an x402-enabled API marketplace that offers a broad set of endpoints spanning data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities. Every endpoint is priced at $0.02 per request, settled in USDC on the Base network via the x402 payment protocol. There are no API keys, no rate limits, and no minimum commitments — callers simply attach an X-PAYMENT header with a valid payment proof to each request.\n\nThe specific endpoint at `/api/v1/keys/81` is listed as \"Premium API Access\" and returns an x402 challenge requesting up to 20,000 base units of USDC (0.02 USD, since USDC uses 6 decimals) on Base. The payment is made to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using the \"exact\" scheme with a 300-second timeout. The response MIME type is `application/json`.\n\nThe platform advertises additional endpoints including sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and generation — all at the same $0.02 price point. However, no OpenAPI schema, detailed documentation, or example request/response payloads are available for any of these endpoints, so the exact input parameters and output formats remain unknown.","tags":[],"capabilities":["x402-payment","usdc-base","pay-per-request","data-analytics","ai-inference","sentiment-analysis","text-summarization","classification","embeddings","finance-data","crypto-quotes","gas-estimates","geocoding","validation","conversion"],"categories":["ai","data","finance","infrastructure"],"synonyms":["low payment fee","x402 api","pay per call api","usdc api","base network api","micropayment api","402 payment api"],"warnings":["No OpenAPI schema or endpoint documentation available","The exact purpose and input/output format of /api/v1/keys/81 is unknown — 'Premium API Access' is vague and may be a key-provisioning endpoint rather than a data API","Crawled /pricing, /api, and /README pages returned no meaningful content (only 'Connect wallet')","No example requests or responses are documented anywhere","Cannot verify that the advertised AI, finance, and utility endpoints actually function"],"endpointUrl":"https://lowpaymentfee.com/api/v1/keys/81","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/keys/81","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.350","qualityRationale":"The endpoint is live and returns a valid x402 challenge, confirming pricing and payment details. However, there is no OpenAPI schema, no documentation beyond a landing page listing, no example requests or responses, and the purpose of the specific `/api/v1/keys/81` endpoint (\"Premium API Access\") is unclear — it may be a meta-endpoint for key generation rather than a data endpoint. The crawled /api, /pricing, and /README pages returned only a wallet-connect prompt with no useful 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'/request':19,38 '0.02':18,37,70,138,198 '000':133 '0x1a2b13e97f5f837c8f9fa1f95a1484b7c70d85f3':153 '20':132 '300':160 '402 payment api' '6':143 'access':123 'addit':172 'address':152 'advertis':171 'ai':12,31,57 'ai-inference' 'analysi':176 'analyt':56 'api':5,24,45,88,122 'application/json':168 'attach':99 'avail':212 'base':8,27,78,134,146 'base network api' 'broad':50 'call':4,23 'caller':97 'challeng':128 'classif':179 'classification' 'commit':96 'convers':191 'conversion' 'cover':10,29 'crypto-quotes' 'data':11,30,55 'data-analytics' 'decim':144 'detail':205 'document':206 'embed':180 'embeddings' 'enabl':44 'endpoint':16,35,53,66,115,173,217 'estim':188 'everi':65 'exact':156,220 'exampl':208 'exchang':183 'feed':182 'financ':13,32,60 'finance-data' 'format':225 'gas':187 'gas-estimates' 'generat':193 'geocod':189 'geocoding' 'header':104 'howev':201 'includ':174 'infrastructur':63 'input':221 'key':89 'learn':59 'limit':92 'list':119 'low payment fee' 'lowpaymentfee.com':39 'machin':58 'made':150 'marketplac':46 'micropayment api' 'mime':165 'minimum':95 'network':79 'offer':48 'openapi':203 'output':224 'paramet':222 'pay':2,21 'pay per call api' 'pay-per-cal':1,20 'pay-per-request' 'payload':210 'payment':83,103,108,148 'per':3,22,71 'platform':6,25,170 'point':200 'premium':121 'price':68,181,199 'proof':109 'protocol':84 'quot':186 'rate':91,184 'remain':226 'request':72,112,129 'request/response':209 'respons':164 'return':125 'schema':204 'scheme':157 'second':161 'sentiment':175 'sentiment-analysis' 'set':51 'settl':73 'simpli':98 'sinc':140 'span':54 'specif':114 'summar':178 'text':177 'text-summarization' 'timeout':162 'token':185 'type':166 'unit':135 'unknown':227 'usd':139 'usdc':9,28,75,137,141 'usdc api' 'usdc-base' 'use':142,154 'util':15,34,64 'valid':107,190 'validation' 'via':80 'web3':61 'x':102 'x-payment':101 'x402':43,82,127 'x402 api' 'x402-enabled':42 'x402-payment'","prices":[{"id":"aa874b91-003d-4e74-9a57-16892fac8485","listingId":"0870f947-edb7-4712-91b4-d4768e3222c0","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/keys/81","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-21T18:32:23.577Z"}],"sources":[{"listingId":"0870f947-edb7-4712-91b4-d4768e3222c0","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/keys/81","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:23.577Z","lastSeenAt":"2026-04-22T01:02:18.935Z"}],"details":{"listingId":"0870f947-edb7-4712-91b4-d4768e3222c0","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/keys/81 \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <x402-payment-proof>\" \\\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 requesting 20,000 base units of USDC on Base (0.02 USD)","source_url":"https://lowpaymentfee.com/api/v1/keys/81"},{"claim":"All listed endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access","source_url":"https://lowpaymentfee.com"},{"claim":"The platform offers endpoints across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categories","source_url":"https://lowpaymentfee.com"},{"claim":"Payment is settled in USDC on the Base network to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3","source_url":"https://lowpaymentfee.com/api/v1/keys/81"}],"useCases":["Agents needing on-demand AI inference (sentiment, summarization, classification, embeddings) without API key management","Fetching real-time crypto token quotes, gas estimates, or exchange rates with per-call billing","Geocoding addresses or validating/converting data via utility endpoints paid in USDC"],"bestFor":["AI agents that need frictionless, keyless API access with crypto micropayments","Developers prototyping with multiple API categories without upfront commitments","Web3-native applications already operating on the Base network with USDC"],"notFor":["High-volume production workloads where $0.02/request adds up significantly without bulk discounts","Users who need detailed API documentation, schemas, or SLAs before integrating"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:05.52Z"},"updatedAt":"2026-04-22T01:02:18.935Z"}}