{"id":"4ad434a6-f637-4ac2-a5a9-a7ac169c25e6","shortId":"RGLYwk","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 site hosts a broad catalog of pay-per-request APIs spanning data & analytics, AI/ML inference (sentiment analysis, 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, payable in USDC on the Base network with no API keys, no rate limits, and no commitments required.\n\nThe specific endpoint `/api/v1/payments/173` is listed as \"Premium API Access\" and returns a valid x402 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, settling to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout. The endpoint accepts POST requests and returns application/json.\n\nDocumentation is extremely sparse — the /docs, /pricing, /api, and /README pages all render only a \"Connect wallet\" prompt with no further content. There is no OpenAPI spec, no request/response schema documentation, and no examples of what this particular endpoint actually returns. The site's landing page lists many API paths but does not describe request parameters or response formats for any of them. Without documentation it is unclear what data or functionality this specific payments/173 endpoint provides beyond its generic \"Premium API Access\" label.","tags":[],"capabilities":["x402-payment","usdc-base","pay-per-request","no-api-key","json-response","post-method"],"categories":["api","payments"],"synonyms":["x402 API","pay-per-call API","USDC micropayment API","Base network API","lowpaymentfee","premium API access","crypto-paid API"],"warnings":["No documentation available — /docs, /pricing, /api, and /README pages all show only 'Connect wallet' with no content","No OpenAPI or schema describing request parameters or response format for this endpoint","The purpose of /api/v1/payments/173 is unclear — 'Premium API Access' is a generic label with no specifics","Cannot verify what data or service is actually returned after successful payment"],"endpointUrl":"https://lowpaymentfee.com/api/v1/payments/173","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/173","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 with clear pricing ($0.02 USDC on Base). However, there is no documentation, no OpenAPI spec, no request/response schema, and no examples of what the endpoint actually does beyond the generic label 'Premium API Access'. The docs/pricing/README pages are all empty wallet-connect 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'/api/v1/payments/173':112 '/docs':172 '/pricing':173 '/readme':176 '/request':13,28 '0.02':12,27,88,141 '000':130 '0x1a2b13e97f5f837c8f9fa1f95a1484b7c70d85f3':153 '0x8335':135 '20':129 '2913':136 '300':156 'Base network API' 'USDC micropayment API' 'accept':161 'access':7,22,38,118,249 'actual':206 'address':152 'ai/ml':59 'analysi':62 'analyt':58 'api':6,21,37,55,100,117,215,248 'application/json':166 'base':9,24,96,131,138 'beyond':244 'broad':48 'call':4,19 'catalog':49 'challeng':124 'classif':64 'commit':107 'connect':182 'content':188 'convers':81 'crypto-paid API' 'data':57,236 'describ':220 'document':167,197,231 'embed':65 'endpoint':32,84,111,160,205,242 'equal':140 'estim':75 'exact':148 'exampl':200 'exchang':70 'extrem':169 'feed':69 'financ':66 'format':225 'function':238 'gas':74 'generat':82 'generic':246 'geocod':79 'host':46 'infer':60 'infrastructur':77 'json-response' 'key':101 'label':250 'land':211 'limit':104 'list':114,213 'lowpaymentfee' 'lowpaymentfee.com':34 'made':144 'mani':214 'maxamountrequir':127 'network':97 'no-api-key' 'openapi':192 'page':177,212 'paramet':222 'particular':204 'path':216 'pay':2,17,52 'pay-per-cal':1,16 'pay-per-call API' 'pay-per-request':51 'payabl':91 'payment':42,142 'payments/173':241 'per':3,18,53,89 'post':162 'post-method' 'premium':5,20,36,116,247 'premium API access' 'price':68,86 'prompt':184 'protocol':43 'provid':35,243 'quot':73 'rate':71,103 'render':179 'request':54,90,163,221 'request/response':195 'requir':108 'respons':224 'return':120,165,207 'schema':196 'scheme':149 'second':157 'sentiment':61 'settl':150 'site':45,209 'span':56 'spars':170 'spec':193 'specif':110,240 'summar':63 'timeout':158 'token':72 'unclear':234 'unit':132 'usdc':15,30,93,134 'usdc-base' 'util':78 'valid':80,122 'via':10,25,39,145 'wallet':183 'web3':67 'without':230 'x402':11,26,41,123,147 'x402 API' 'x402-payment'","prices":[{"id":"1fa61170-1806-48e7-8ac7-00478e95489d","listingId":"4ad434a6-f637-4ac2-a5a9-a7ac169c25e6","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/173","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:49:35.356Z"}],"sources":[{"listingId":"4ad434a6-f637-4ac2-a5a9-a7ac169c25e6","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/payments/173","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:49:35.356Z","lastSeenAt":"2026-04-22T10:01:56.562Z"}],"details":{"listingId":"4ad434a6-f637-4ac2-a5a9-a7ac169c25e6","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/payments/173\n# Returns 402 with x402 challenge. Include X-PAYMENT header with valid payment proof to access.","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/173","description":"Premium API Access","maxAmountRequired":"20000","maxTimeoutSeconds":300}],"x402Version":1},"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"All endpoints 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 site offers APIs across data & analytics, AI/ML, finance & Web3, and infrastructure categories","source_url":"https://lowpaymentfee.com"},{"claim":"x402 challenge returns maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base","source_url":"https://lowpaymentfee.com/api/v1/payments/173"}],"useCases":["Accessing premium API functionality with per-request USDC micropayments on Base","Agent-driven API consumption without pre-registration or API keys","Programmatic pay-as-you-go access to data or services"],"bestFor":["Developers wanting keyless, pay-per-use API access","AI agents that can settle x402 payments autonomously","Users already holding USDC on Base who want frictionless API calls"],"notFor":["Users needing detailed API documentation or request/response schemas before integrating","Anyone without USDC on the Base network","High-volume use cases where per-request payment overhead is impractical"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:09.431Z"},"updatedAt":"2026-04-22T10:01:56.562Z"}}