{"id":"bc8573c0-ea83-48fb-83cf-be3ff8c84e53","shortId":"YWppnc","kind":"x402","title":"x402-gated portfolio endpoint on Base, pay $0.02 per request in USDC — no API keys required.","tagline":"x402-gated portfolio endpoint on Base, pay $0.02 per request in USDC — no API keys required.","description":"This endpoint at lowpaymentfee.com provides premium API access to a portfolio resource (`/api/v1/portfolios/3`) via the x402 payment protocol. It is part of a broader platform offering data & analytics, AI/ML inference, finance/Web3 data, and infrastructure utility endpoints — all gated behind per-request micropayments settled in USDC on the Base network.\n\nThe specific `/api/v1/portfolios/3` endpoint accepts POST requests and returns JSON. The x402 challenge advertises a maximum cost of 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 per request (USDC uses 6 decimals). The platform's landing page confirms a flat $0.02/request pricing model across all endpoints with no API keys, no rate limits, and no minimum commitments.\n\nDocumentation is extremely sparse — 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 usage examples available. The endpoint name \"portfolios/3\" and the description \"Premium API Access\" give very little indication of what data is actually returned. The endpoint is confirmed live (402 challenge captured), but without documentation it is difficult to know what request body to send or what response to expect.","tags":[],"capabilities":["x402-payment","usdc-micropayment","base-network","per-request-billing","no-api-key","json-response","post-endpoint"],"categories":["finance","data"],"synonyms":["portfolio API","x402 API","micropayment API","pay-per-request API","USDC gated endpoint","lowpaymentfee","Base network API","crypto payment API"],"warnings":["No documentation available — /docs, /pricing, /api, and /README all render only a 'Connect wallet' prompt with no content.","No OpenAPI or schema definition found; request body format and response structure are unknown.","The specific resource '/api/v1/portfolios/3' is undocumented — it is unclear what 'portfolios/3' refers to or what data it returns.","This endpoint is not listed on the provider's own landing page among their advertised APIs, raising questions about its status."],"endpointUrl":"https://lowpaymentfee.com/api/v1/portfolios/3","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/3","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 x402 402 challenge, and pricing is clear ($0.02/request in USDC on Base). However, there is no OpenAPI spec, no documentation beyond a wallet-connect prompt, no request/response schema, and no examples. The purpose of '/api/v1/portfolios/3' is entirely opaque. This is effectively a stub 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'/api/v1/portfolios/3':47,87 '/docs':153 '/pricing':155 '/readme':157 '/request':131 '0.02':9,26,115,130 '000':104 '0x8335':109 '20':103 '2913':110 '402':209 '6':120 'Base network API' 'USDC gated endpoint' 'accept':89 'access':42,193 'across':134 'actual':202 'advertis':98 'ai/ml':63 'analyt':62 'api':15,32,41,139,192 'avail':183 'base':7,24,83,105,112 'base-network' 'behind':73 'bodi':222 'broader':58 'captur':211 'challeng':97,210 'commit':147 'confirm':127,207 'connect':163 'content':169 'cost':101 'crypto payment API' 'data':61,66,200 'decim':121 'descript':190 'difficult':217 'document':148,178,214 'endpoint':5,22,36,70,88,136,185,205 'equal':114 'exampl':182 'expect':229 'extrem':150 'finance/web3':65 'flat':129 'gate':3,20,72 'give':194 'indic':197 'infer':64 'infrastructur':68 'json':94 'json-response' 'key':16,33,140 'know':219 'land':125 'limit':143 'littl':196 'live':208 'lowpaymentfee' 'lowpaymentfee.com':38 'maximum':100 'micropay':77 'micropayment API' 'minimum':146 'model':133 'name':186 'network':84 'no-api-key' 'offer':60 'openapi':173 'page':126,158 'part':55 'pay':8,25 'pay-per-request API' 'payment':51 'per':10,27,75,116 'per-request':74 'per-request-billing' 'platform':59,123 'portfolio':4,21,45 'portfolio API' 'portfolios/3':187 'post':90 'post-endpoint' 'premium':40,191 'price':132 'prompt':165 'protocol':52 'provid':39 'rate':142 'render':160 'request':11,28,76,91,117,221 'request/response':176 'requir':17,34 'resourc':46 'respons':227 'return':93,203 'schema':177 'send':224 'settl':78 'spars':151 'spec':174 'specif':86 'unit':106 'usag':181 'usdc':13,30,80,108,118 'usdc-micropayment' 'use':119 'util':69 'via':48 'wallet':164 'without':213 'x402':2,19,50,96 'x402 API' 'x402-gated':1,18 'x402-payment'","prices":[{"id":"81b56d64-8086-413e-a73b-dc8e43869746","listingId":"bc8573c0-ea83-48fb-83cf-be3ff8c84e53","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/3","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:52:32.073Z"}],"sources":[{"listingId":"bc8573c0-ea83-48fb-83cf-be3ff8c84e53","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/portfolios/3","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:52:32.073Z","lastSeenAt":"2026-04-28T03:05:37.418Z"}],"details":{"listingId":"bc8573c0-ea83-48fb-83cf-be3ff8c84e53","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/portfolios/3 \\\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 x402 challenge advertises maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base network","source_url":"https://lowpaymentfee.com/api/v1/portfolios/3"},{"claim":"Platform pricing is $0.02 per request with no API keys, no rate limits, and instant access on Base network","source_url":"https://lowpaymentfee.com"},{"claim":"The platform offers endpoints across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categories","source_url":"https://lowpaymentfee.com"}],"useCases":["Accessing portfolio data with per-request USDC micropayments on Base","Integrating pay-per-call APIs into autonomous agents without API key management","Consuming premium data feeds where traditional subscription models are undesirable"],"bestFor":["Developers experimenting with x402 payment protocol integrations","Agents or bots that need keyless, pay-as-you-go API access","Low-volume consumers who want to avoid subscription commitments"],"notFor":["Users who need detailed API documentation or request/response schemas before integrating","High-volume consumers who would benefit from bulk pricing or subscription plans","Anyone without a Base-compatible USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:00.983Z"},"updatedAt":"2026-04-28T03:05:37.418Z"}}