{"id":"7a849d1e-9523-4c8f-9ee6-e1e53952ea4d","shortId":"Y7t4Z6","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 pay-per-call APIs gated by the x402 protocol on the Base network. The endpoint at `/api/v1/collections/23` is listed as \"Premium API Access\" and returns a standard x402 challenge requesting payment in USDC (contract 0x8335…2913 on Base). The maximum amount required per call is 20,000 base units of USDC (6 decimals), which equals $0.02 USD. Payment is made via the x402 exact scheme with no API keys, subscriptions, or rate limits advertised.\n\nThe broader platform advertises four categories of endpoints: 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 the same $0.02/request price point. However, the specific endpoint `/api/v1/collections/23` does not clearly map to any single one of these categories — it may be a collection or bundle endpoint.\n\nDocumentation is extremely thin. The docs, API, pricing, and README pages all render only a \"Connect wallet\" prompt with no further content visible to crawlers. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available. The endpoint is confirmed live (402 challenge captured), but without documentation it is unclear what data or functionality this specific collection endpoint returns.","tags":[],"capabilities":["x402-payment","usdc-settlement","base-network","pay-per-request","no-api-key","json-response"],"categories":["api-gateway","data"],"synonyms":["x402 API","pay-per-call API","USDC micropayment API","Base network API","lowpaymentfee","crypto-gated API","serverless API payment"],"warnings":["No API documentation available — docs, pricing, and README pages only show 'Connect wallet'","No OpenAPI or schema definition found for this endpoint","The purpose and response format of /api/v1/collections/23 is undocumented and unclear","No request body schema or example responses available"],"endpointUrl":"https://lowpaymentfee.com/api/v1/collections/23","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/23","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.300","qualityRationale":"The endpoint is confirmed live with a valid x402 challenge and clear pricing ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond a wallet-connect prompt, and no examples. The specific purpose of /api/v1/collections/23 is unclear. This is effectively a stub 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'/request':162 '0.02':9,25,94,161 '000':85 '0x8335':73 '20':84 '2913':74 '402':233 '6':90 'Base network API' 'USDC micropayment API' 'access':61 'advertis':112,116 'ai':128 'amount':79 'analysi':132 'analyt':122 'api':4,20,42,60,106,195 'avail':227 'base':7,23,50,76,86 'base-network' 'broader':114 'bundl':187 'call':41,82 'captur':235 'categori':118,180 'challeng':67,234 'classif':135 'clear':172 'collect':5,21,185,248 'confirm':231 'connect':204 'content':210 'contract':72 'convers':152 'crawler':213 'crypto-gated API' 'data':121,125,243 'decim':91 'doc':194 'document':189,222,238 'embed':136 'endpoint':53,120,155,168,188,229,249 'equal':93 'estim':146 'exact':102 'exampl':226 'exchang':141 'export':126 'extrem':191 'feed':140 'financ':137 'four':117 'function':245 'gas':145 'gate':3,19,43 'generat':153 'geocod':150 'host':34 'howev':165 'infrastructur':148 'insight':127 'json-response' 'key':15,31,107 'learn':130 'limit':111 'list':57,157 'live':232 'lowpaymentfee' 'lowpaymentfee.com':33 'machin':129 'made':98 'map':173 'maximum':78 'may':182 'metric':123 'network':51 'no-api-key' 'one':177 'openapi':217 'page':199 'pay':8,24,39 'pay-per-cal':38 'pay-per-call API' 'pay-per-request' 'payment':69,96 'per':10,26,40,81 'platform':115 'point':164 'premium':59 'price':139,163,196 'prompt':206 'protocol':47 'quot':144 'rate':110,142 'readm':198 'render':201 'report':124 'request':11,27,68 'request/response':220 'requir':16,32,80 'return':63,250 'schema':221 'scheme':103 'sentiment':131 'serverless API payment' 'singl':176 'spec':218 'specif':167,247 'standard':65 'subscript':108 'suit':36 'summar':134 'text':133 'thin':192 'token':143 'unclear':241 'unit':87 'usag':225 'usd':95 'usdc':13,29,71,89 'usdc-settlement' 'util':149 'valid':151 'via':99 'visibl':211 'wallet':205 'web3':138 'without':237 'x402':2,18,46,66,101 'x402 API' 'x402-gated':1,17 'x402-payment'","prices":[{"id":"36d67c01-e611-49e8-bc37-86b0f2ba7d28","listingId":"7a849d1e-9523-4c8f-9ee6-e1e53952ea4d","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/23","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T22:29:47.064Z"}],"sources":[{"listingId":"7a849d1e-9523-4c8f-9ee6-e1e53952ea4d","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/collections/23","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T22:29:47.064Z","lastSeenAt":"2026-04-22T05:31:54.843Z"}],"details":{"listingId":"7a849d1e-9523-4c8f-9ee6-e1e53952ea4d","quickStartSnippet":"# 1. Send a POST to get the 402 challenge\ncurl -X POST https://lowpaymentfee.com/api/v1/collections/23\n# 2. Pay the x402 challenge (20000 base units USDC on Base)\n#    Attach the signed payment in the X-PAYMENT header:\ncurl -X POST https://lowpaymentfee.com/api/v1/collections/23 \\\n  -H 'X-PAYMENT: <signed-x402-payment-token>' \\\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 requesting 20000 base units of USDC on Base network","source_url":"https://lowpaymentfee.com/api/v1/collections/23"},{"claim":"USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base","source_url":"https://lowpaymentfee.com/api/v1/collections/23"},{"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 Data & Analytics, AI & ML, Finance & Web3, and Infrastructure endpoint categories","source_url":"https://lowpaymentfee.com"}],"useCases":["Accessing premium data or AI endpoints without creating an account or managing API keys","Making one-off API calls paid in USDC on Base with no subscription commitment","Agent-driven workflows that need programmatic, wallet-authenticated API access"],"bestFor":["Developers who want zero-friction, pay-as-you-go API access via crypto","AI agents with Base USDC wallets needing on-demand API calls","Prototyping and low-volume usage where $0.02/request is cost-effective"],"notFor":["High-volume production workloads where per-request crypto payment adds latency","Users without a Base-compatible wallet or USDC holdings","Anyone needing detailed API documentation or SLA guarantees"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:25.278Z"},"updatedAt":"2026-04-22T05:31:54.843Z"}}