{"id":"e48f7484-bfb5-4897-9c31-f3947ea73382","shortId":"AfvXvc","kind":"x402","title":"Pay-per-call API platform on Base network via x402 — $0.02/request in USDC.","tagline":"Pay-per-call API platform on Base network via x402 — $0.02/request in USDC.","description":"lowpaymentfee.com is an x402-enabled API platform that offers a variety of endpoints across data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. All endpoints are paid per-request using USDC on the Base network, with no API keys, no rate limits, and no commitments required. The specific endpoint at `/api/v1/transactions/253` is labeled \"Premium API Access\" and accepts x402 payments.\n\nThe platform advertises a flat $0.02 per request across its listed endpoints. The probed endpoint's x402 challenge shows a `maxAmountRequired` of 20000 in USDC (6 decimals), which equals $0.02 — consistent with the site's stated pricing. Payment is settled on-chain to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using USDC contract `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913` on Base.\n\nThe broader platform lists endpoints for 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, documentation is extremely sparse: the docs, API, pricing, and README pages all render only a \"Connect wallet\" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawled content. The specific functionality of the `/api/v1/transactions/253` endpoint beyond its \"Premium API Access\" label is unknown.","tags":[],"capabilities":["x402-payment","usdc-base","pay-per-request","no-api-key","data-analytics","ai-inference","finance-data","web3-data","geocoding","text-summarization","sentiment-analysis","embeddings"],"categories":["api-platform","llm","finance","geo"],"synonyms":["x402 API","pay-per-call API","USDC API","Base network API","micropayment API","lowpaymentfee","crypto-paid API"],"warnings":["No OpenAPI or schema documentation available — all docs/pricing/README pages return only 'Connect wallet'","The specific functionality of /api/v1/transactions/253 ('Premium API Access') is undocumented","No request or response examples available; input format is unknown","The platform lists many endpoint categories but none have documented schemas or usage guides"],"endpointUrl":"https://lowpaymentfee.com/api/v1/transactions/253","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/transactions/253","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 spec, no request/response schema, no documentation beyond a wallet-connect prompt, and the specific purpose of the /api/v1/transactions/253 endpoint is undefined. Effectively a stub 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'/request':13,28 '0.02':12,27,97,121,173 '0x1a2b13e97f5f837c8f9fa1f95a1484b7c70d85f3':137 '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913':141 '20000':114 '6':117 'Base network API' 'USDC API' 'accept':89 'access':87,229 'across':45,100 'address':136 'advertis':94 'ai-inference' 'ai/ml':48 'analysi':151 'analyt':47 'api':5,20,37,69,86,183,228 'avail':213 'base':8,23,65,143 'beyond':225 'broader':145 'call':4,19 'chain':134 'challeng':109 'classif':154 'commit':76 'connect':192 'consist':122 'content':217 'contract':140 'convers':166 'crawl':216 'crypto-paid API' 'data':46 'data-analytics' 'decim':118 'detail':199 'doc':182 'document':177,208 'embed':155 'embeddings' 'enabl':36 'endpoint':44,55,80,103,106,148,224 'equal':120 'estim':163 'exampl':212 'exchang':158 'extrem':179 'feed':157 'finance-data' 'finance/web3':50 'flat':96 'function':220 'gas':162 'generat':168 'geocod':164 'geocoding' 'howev':176 'infer':49 'infrastructur':52 'key':70 'label':84,230 'limit':73 'list':102,147 'lowpaymentfee' 'lowpaymentfee.com':31 'maxamountrequir':112 'micropayment API' 'network':9,24,66 'no-api-key' 'offer':40 'on-chain':132 'openapi':203 'page':187 'paid':57 'pay':2,17 'pay-per-cal':1,16 'pay-per-call API' 'pay-per-request' 'payment':91,129 'per':3,18,59,98 'per-request':58 'platform':6,21,38,93,146 'point':175 'premium':85,227 'price':128,156,174,184 'probe':105 'prompt':194 'quot':161 'rate':72,159 'readm':186 'render':189 'request':60,99 'request/response':206 'requir':77 'schema':207 'sentiment':150 'sentiment-analysis' 'settl':131 'show':110 'site':125 'spars':180 'spec':204 'specif':79,219 'state':127 'summar':153 'technic':198 'text':152 'text-summarization' 'token':160 'unknown':232 'usag':211 'usdc':15,30,62,116,139 'usdc-base' 'use':61,138 'util':53 'valid':165 'varieti':42 'via':10,25 'wallet':193 'web3-data' 'x402':11,26,35,90,108 'x402 API' 'x402-enabled':34 'x402-payment'","prices":[{"id":"c2c9b2a7-1d20-4408-a7df-b80df1499f82","listingId":"e48f7484-bfb5-4897-9c31-f3947ea73382","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/transactions/253","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:59:43.461Z"}],"sources":[{"listingId":"e48f7484-bfb5-4897-9c31-f3947ea73382","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/transactions/253","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:59:43.461Z","lastSeenAt":"2026-04-22T19:32:16.734Z"}],"details":{"listingId":"e48f7484-bfb5-4897-9c31-f3947ea73382","quickStartSnippet":"# The endpoint requires an x402 payment header (USDC on Base).\n# Use an x402-compatible client to auto-negotiate payment.\n\ncurl -X POST https://lowpaymentfee.com/api/v1/transactions/253 \\\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":"Flat pricing of $0.02 per request with no API keys, no rate limits, and instant access on Base network","source_url":"https://lowpaymentfee.com"},{"claim":"x402 challenge returns maxAmountRequired of 20000 USDC (6 decimals = $0.02) on Base network","source_url":"https://lowpaymentfee.com/api/v1/transactions/253"},{"claim":"USDC asset contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base","source_url":"https://lowpaymentfee.com/api/v1/transactions/253"},{"claim":"Platform lists endpoints for analytics, AI/ML, finance/Web3, and infrastructure utilities","source_url":"https://lowpaymentfee.com"}],"useCases":["Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key registration","Fetching real-time crypto token quotes and gas estimates via per-request USDC payments","Running geocoding or data validation utilities with zero commitment"],"bestFor":["Developers wanting instant API access without signup or API keys","Agents that can settle x402 payments in USDC on Base","Low-volume or exploratory use cases where per-call pricing is preferred"],"notFor":["High-volume production workloads where subscription pricing would be cheaper","Users who cannot transact in USDC on the Base network","Anyone needing detailed API documentation or guaranteed SLAs"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:40.403Z"},"updatedAt":"2026-04-22T19:32:16.734Z"}}