{"id":"55fb3f3b-d4f8-4334-9f46-00b603da1c1d","shortId":"9cUdbh","kind":"x402","title":"x402-gated API collection on Base — pay $0.02 per request in USDC, no keys required.","tagline":"x402-gated API collection on Base — pay $0.02 per request in USDC, no keys required.","description":"lowpaymentfee.com hosts a suite of x402-protocol pay-per-call APIs spanning data analytics, AI/ML inference, finance/Web3 data, and utility services. Every endpoint costs $0.02 per request, settled in USDC on the Base network. There are no API keys, no rate limits, and no upfront commitments — callers simply attach an X-PAYMENT header with a valid x402 payment proof.\n\nThe specific endpoint `/api/v1/collections/49` is listed as \"Premium API Access\" and returns an x402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. The payment scheme is \"exact\" with a 300-second timeout. The endpoint accepts POST requests and returns `application/json`.\n\nDocumentation is extremely thin — 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, and no usage examples available from the crawled material. The site's landing page lists many other endpoints in the same pattern (analytics, AI, finance, infrastructure), all at $0.02 each, but provides no detail on request formats or response payloads for any of them. Prospective users should expect to experiment or contact the provider for integration guidance.","tags":[],"capabilities":["x402-payment","pay-per-request","usdc-settlement","base-network","no-api-key","json-response","post-method"],"categories":["api-gateway","pay-per-call"],"synonyms":["x402 API","pay per call API","USDC micropayment API","Base network API","lowpaymentfee","low payment fee API","402 payment required API"],"warnings":["No OpenAPI or schema available — request and response formats are unknown.","Documentation pages (/docs, /pricing, /api, /README) all render only 'Connect wallet' with no usable content.","The purpose of '/api/v1/collections/49' ('Premium API Access') is vague — it is unclear what data or service it provides.","No examples or integration guides found anywhere in the crawled material."],"endpointUrl":"https://lowpaymentfee.com/api/v1/collections/49","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/collections/49","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.300","qualityRationale":"The endpoint is live and returns a valid x402 challenge, confirming it works. However, there is no OpenAPI spec, no request/response schema, no documentation beyond a landing page listing, and no examples. The actual functionality behind 'Premium API Access' and 'collections/49' is completely 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'0.02':9,25,59,125,207 '000':114 '0x8335':119 '20':113 '2913':120 '300':138 '402 payment required API' '6':129 'Base network API' 'USDC micropayment API' 'accept':143 'access':104 'ai':202 'ai/ml':49 'analyt':48,201 'api':4,20,45,72,103,156 'application/json':148 'attach':83 'avail':183 'base':7,23,67,115,122 'base-network' 'call':44 'caller':81 'challeng':109 'collect':5,21 'commit':80 'connect':164 'contact':230 'content':170 'cost':58 'crawl':186 'data':47,52 'decim':130 'detail':212 'doc':154 'document':149 'endpoint':57,97,142,196 'equal':124 'everi':56 'exact':135 'exampl':182 'expect':226 'experi':228 'extrem':151 'financ':203 'finance/web3':51 'format':215 'gate':3,19 'given':126 'guidanc':235 'header':88 'host':34 'infer':50 'infrastructur':204 'integr':234 'json-response' 'key':15,31,73 'land':191 'limit':76 'list':100,193 'low payment fee API' 'lowpaymentfee' 'lowpaymentfee.com':33 'mani':194 'materi':187 'network':68 'no-api-key' 'openapi':174 'page':159,192 'pattern':200 'pay':8,24,42 'pay per call API' 'pay-per-cal':41 'pay-per-request' 'payload':218 'payment':87,93,132 'per':10,26,43,60 'post':144 'post-method' 'premium':102 'price':155 'prompt':166 'proof':94 'prospect':223 'protocol':40 'provid':210,232 'rate':75 'readm':158 'render':161 'request':11,27,61,110,145,214 'request/response':177 'requir':16,32 'respons':217 'return':106,147 'schema':178 'scheme':133 'second':139 'servic':55 'settl':62 'simpli':82 'site':189 'span':46 'spec':175 'specif':96 'suit':36 'thin':152 'timeout':140 'unit':116 'upfront':79 'usag':181 'usdc':13,29,64,118,127 'usdc-settlement' 'user':224 'util':54 'valid':91 'wallet':165 'x':86 'x-payment':85 'x402':2,18,39,92,108 'x402 API' 'x402-gated':1,17 'x402-payment' 'x402-protocol':38","prices":[{"id":"52d36ddd-3361-4c1d-850a-170b7e7c9492","listingId":"55fb3f3b-d4f8-4334-9f46-00b603da1c1d","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/collections/49","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-19T05:29:52.881Z"}],"sources":[{"listingId":"55fb3f3b-d4f8-4334-9f46-00b603da1c1d","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/collections/49","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-19T05:29:52.881Z","lastSeenAt":"2026-04-22T04:02:21.143Z"}],"details":{"listingId":"55fb3f3b-d4f8-4334-9f46-00b603da1c1d","quickStartSnippet":"# 1. POST to the endpoint — you'll get a 402 challenge:\ncurl -X POST https://lowpaymentfee.com/api/v1/collections/49\n\n# 2. Parse the 402 JSON to get payment details, sign a payment proof,\n#    then re-send with the X-PAYMENT header:\ncurl -X POST https://lowpaymentfee.com/api/v1/collections/49 \\\n  -H \"X-PAYMENT: <signed-payment-proof>\" \\\n  -H \"Content-Type: application/json\"","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","source_url":"https://lowpaymentfee.com/api/v1/collections/49"},{"claim":"USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base network","source_url":"https://lowpaymentfee.com/api/v1/collections/49"},{"claim":"All listed APIs cost $0.02 per request with no API keys, no rate limits, and instant access","source_url":"https://lowpaymentfee.com"},{"claim":"The site lists endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories","source_url":"https://lowpaymentfee.com"}],"useCases":["Accessing premium API data without managing API keys or subscriptions","Agent-driven workflows that need on-demand paid API calls settled in USDC","Programmatic access to a collection endpoint with per-request crypto payment"],"bestFor":["Developers who want zero-signup, pay-as-you-go API access","AI agents with x402-compatible wallets on Base","Users who prefer crypto micropayments over traditional billing"],"notFor":["Users who need detailed API documentation or OpenAPI specs before integrating","High-volume consumers who want bulk pricing or subscription discounts","Developers without a Base-network USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:24.436Z"},"updatedAt":"2026-04-22T04:02:21.143Z"}}