{"id":"03453da1-aa06-4bbd-976a-0a06166af953","shortId":"m2LPvn","kind":"x402","title":"x402-gated portfolio endpoint on Base, pay $0.02 per request in USDC — no API keys needed.","tagline":"x402-gated portfolio endpoint on Base, pay $0.02 per request in USDC — no API keys needed.","description":"This endpoint at lowpaymentfee.com exposes a portfolio resource at `/api/v1/portfolios/37` behind an x402 paywall. It is part of a broader platform offering dozens of pay-per-call APIs spanning data analytics, AI/ML inference, finance/Web3 data, and utility services — all priced at $0.02 per request settled in USDC on the Base network.\n\nThe specific `/api/v1/portfolios/37` endpoint accepts POST requests and returns JSON. The x402 challenge confirms the endpoint is live, advertising a max amount of 20,000 base units of USDC (0x8335…2913 on Base, 6 decimals), which equals $0.02. Payment is made via the x402 exact scheme with no API key or account required; callers attach an `X-PAYMENT` header to settle each request on-chain.\n\nDocumentation beyond the landing page is extremely thin — the /docs, /api, /pricing, 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 description of what the portfolios/37 resource actually returns. The endpoint's purpose (portfolio data, financial analysis, or something else) must be inferred from the URL path alone, making integration speculative without trial calls.","tags":[],"capabilities":["x402-payment","per-request-billing","usdc-base","no-api-key","json-response","post-method","portfolio-data"],"categories":["finance","data"],"synonyms":["portfolio API","x402 API","pay-per-call API","USDC micropayment API","Base network API","lowpaymentfee","crypto payment API","402 payment endpoint"],"warnings":["No documentation available — /docs, /pricing, /api, and /README pages all show only a 'Connect wallet' prompt with no content.","No OpenAPI or schema describing request parameters or response format for /api/v1/portfolios/37.","The purpose of the 'portfolios/37' resource is unclear; the endpoint name is the only hint.","Cannot verify what data is actually returned without making a paid request."],"endpointUrl":"https://lowpaymentfee.com/api/v1/portfolios/37","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/portfolios/37","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 via a valid 402 challenge with clear pricing ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation of what the portfolios/37 resource returns, and all doc pages render only a wallet-connect prompt. The listing is effectively a 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'/api/v1/portfolios/37':44,89 '/docs':163 '/pricing':165 '/readme':167 '0.02':9,26,77,124 '000':111 '0x8335':116 '20':110 '2913':117 '402 payment endpoint' '6':120 'Base network API' 'USDC micropayment API' 'accept':91 'account':138 'actual':197 'advertis':105 'ai/ml':67 'alon':217 'amount':108 'analysi':206 'analyt':66 'api':15,32,63,135 'attach':141 'base':7,24,85,112,119 'behind':45 'beyond':155 'broader':54 'call':62,223 'caller':140 'chain':153 'challeng':99 'confirm':100 'connect':173 'content':179 'crypto payment API' 'data':65,70,204 'decim':121 'descript':191 'document':154,188 'dozen':57 'els':209 'endpoint':5,22,36,90,102,200 'equal':123 'exact':131 'expos':39 'extrem':160 'finance/web3':69 'financi':205 'gate':3,20 'header':146 'infer':68,212 'integr':219 'json':96 'json-response' 'key':16,33,136 'land':157 'live':104 'lowpaymentfee' 'lowpaymentfee.com':38 'made':127 'make':218 'max':107 'must':210 'need':17,34 'network':86 'no-api-key' 'offer':56 'on-chain':151 'openapi':183 'page':158,168 'part':51 'path':216 'pay':8,25,60 'pay-per-cal':59 'pay-per-call API' 'payment':125,145 'paywal':48 'per':10,27,61,78 'per-request-billing' 'platform':55 'portfolio':4,21,41,203 'portfolio API' 'portfolio-data' 'portfolios/37':195 'post':92 'post-method' 'price':75 'prompt':175 'purpos':202 'render':170 'request':11,28,79,93,150 'request/response':186 'requir':139 'resourc':42,196 'return':95,198 'schema':187 'scheme':132 'servic':73 'settl':80,148 'someth':208 'span':64 'spec':184 'specif':88 'specul':220 'thin':161 'trial':222 'unit':113 'url':215 'usdc':13,30,82,115 'usdc-base' 'util':72 'via':128 'wallet':174 'without':221 'x':144 'x-payment':143 'x402':2,19,47,98,130 'x402 API' 'x402-gated':1,18 'x402-payment'","prices":[{"id":"ed2adf2a-b255-4b49-afa5-dd4cdfa3ae95","listingId":"03453da1-aa06-4bbd-976a-0a06166af953","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/portfolios/37","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:52:38.743Z"}],"sources":[{"listingId":"03453da1-aa06-4bbd-976a-0a06166af953","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/portfolios/37","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:52:38.743Z","lastSeenAt":"2026-04-27T22:33:20.567Z"}],"details":{"listingId":"03453da1-aa06-4bbd-976a-0a06166af953","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/portfolios/37 \\\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":"The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Base (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913).","source_url":"https://lowpaymentfee.com/api/v1/portfolios/37"},{"claim":"The platform advertises $0.02 per request pricing with no API keys, no rate limits, and instant access on the Base network.","source_url":"https://lowpaymentfee.com"},{"claim":"The platform offers APIs across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categories.","source_url":"https://lowpaymentfee.com"}],"useCases":["Fetching portfolio data or analytics for portfolio ID 37 via a single paid request","Integrating pay-per-call financial data into an AI agent workflow without managing API keys","Demonstrating x402 protocol payment flows on the Base network"],"bestFor":["Developers experimenting with x402 payment protocol","Agents needing keyless, on-demand API access settled in USDC","Low-volume consumers who prefer pay-per-request over subscriptions"],"notFor":["Users who need detailed API documentation before integrating","High-volume consumers who need bulk pricing or rate-limit guarantees","Anyone without a Base-network USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:00.642Z"},"updatedAt":"2026-04-27T22:33:20.567Z"}}