{"id":"c4c61e21-cf13-4753-ba55-434eb22dfc1f","shortId":"jpKeUj","kind":"x402","title":"x402-gated portfolio data endpoint on Base, pay $0.02 per request in USDC.","tagline":"x402-gated portfolio data endpoint on Base, pay $0.02 per request in USDC.","description":"This endpoint at lowpaymentfee.com provides access to a specific portfolio resource (portfolio ID 21) via the x402 payment protocol. The endpoint is live and returns a 402 challenge requiring payment in USDC on the Base network. Each request costs $0.02 (20,000 base units of USDC with 6 decimals). Payment is settled on-chain to the specified wallet address, with no API keys, rate limits, or subscriptions required.\n\nThe provider lowpaymentfee.com hosts a broader suite of x402-gated APIs spanning 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 $0.02 per request.\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 schema, no request/response examples, and no description of what the portfolio endpoint actually returns. The endpoint accepts POST requests and returns application/json, but the exact payload structure is unknown.","tags":[],"capabilities":["x402-payment","usdc-settlement","base-network","portfolio-data","per-request-pricing","no-api-key","json-response"],"categories":["finance","data"],"synonyms":["portfolio API","x402 portfolio","pay-per-request API","USDC API","Base network API","lowpaymentfee","crypto payment API","402 payment endpoint"],"warnings":["No documentation available — docs, API, pricing, and README pages all show only 'Connect wallet' with no content.","No OpenAPI or request/response schema provided; the actual data returned by /api/v1/portfolios/21 is completely unknown.","The specific purpose of 'portfolio 21' is undocumented; it is unclear what data this resource represents.","Cannot verify the quality or accuracy of returned data without any example responses."],"endpointUrl":"https://lowpaymentfee.com/api/v1/portfolios/21","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/21","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, but there is zero documentation on what the portfolio endpoint accepts or returns. No OpenAPI schema, no examples, and all doc pages are empty beyond a wallet connect prompt. The listing is effectively a 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'000':70 '20':69 '21':42 '402':55 '402 payment endpoint' '6':76 'Base network API' 'USDC API' 'accept':194 'access':34 'actual':190 'address':88 'ai':118 'analysi':122 'analyt':112 'api':91,109,158 'application/json':199 'base':8,22,63,71 'base-network' 'broader':103 'chain':83 'challeng':56 'classif':125 'connect':167 'content':173 'convers':142 'cost':67 'crypto payment API' 'data':5,19,111,115 'decim':77 'descript':184 'doc':157 'document':152 'embed':126 'endpoint':6,20,30,49,145,189,193 'estim':136 'exact':202 'exampl':181 'exchang':131 'export':116 'extrem':154 'feed':130 'financ':127 'gas':135 'gate':3,17,108 'generat':143 'geocod':140 'host':101 'id':41 'infrastructur':138 'insight':117 'json-response' 'key':92 'learn':120 'limit':94 'list':147 'live':51 'lowpaymentfee' 'lowpaymentfee.com':32,100 'machin':119 'metric':113 'network':64 'no-api-key' 'on-chain':81 'openapi':177 'page':162 'pay':9,23 'pay-per-request API' 'payload':203 'payment':46,58,78 'per':11,25,150 'per-request-pricing' 'portfolio':4,18,38,40,188 'portfolio API' 'portfolio-data' 'post':195 'price':129,159 'prompt':169 'protocol':47 'provid':33,99 'quot':134 'rate':93,132 'readm':161 'render':164 'report':114 'request':12,26,66,151,196 'request/response':180 'requir':57,97 'resourc':39 'return':53,191,198 'schema':178 'sentiment':121 'settl':80 'span':110 'spars':155 'specif':37 'specifi':86 'structur':204 'subscript':96 'suit':104 'summar':124 'text':123 'token':133 'unit':72 'unknown':206 'usdc':14,28,60,74 'usdc-settlement' 'util':139 'valid':141 'via':43 'wallet':87,168 'web3':128 'x402':2,16,45,107 'x402 portfolio' 'x402-gated':1,15,106 'x402-payment'","prices":[{"id":"aba04efe-eaff-47da-965d-de0a47ee42df","listingId":"c4c61e21-cf13-4753-ba55-434eb22dfc1f","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/21","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:52:27.857Z"}],"sources":[{"listingId":"c4c61e21-cf13-4753-ba55-434eb22dfc1f","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/portfolios/21","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:52:27.857Z","lastSeenAt":"2026-04-28T05:04:34.815Z"}],"details":{"listingId":"c4c61e21-cf13-4753-ba55-434eb22dfc1f","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/portfolios/21 \\\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":"Endpoint returns HTTP 402 with x402 challenge requiring USDC payment on Base network","source_url":"https://lowpaymentfee.com/api/v1/portfolios/21"},{"claim":"maxAmountRequired is 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913), equating to $0.02","source_url":"https://lowpaymentfee.com/api/v1/portfolios/21"},{"claim":"All endpoints priced at $0.02 per request with no API keys, no rate limits, instant access on Base network","source_url":"https://lowpaymentfee.com"},{"claim":"Provider offers APIs across data & analytics, AI & ML, finance & Web3, and infrastructure categories","source_url":"https://lowpaymentfee.com"}],"useCases":["Fetching portfolio data on-demand with per-request USDC micropayments","Agent-driven access to financial portfolio information without API key management","Integrating pay-per-call portfolio lookups into automated trading or analytics pipelines"],"bestFor":["Developers wanting keyless, pay-per-use API access settled in USDC on Base","AI agents that can handle x402 payment challenges natively","Users who prefer on-chain micropayments over subscription billing"],"notFor":["Users who need detailed API documentation or request/response schemas before integrating","High-volume consumers who would benefit from bulk pricing or subscriptions","Anyone without a Base-compatible USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:01.151Z"},"updatedAt":"2026-04-28T05:04:34.815Z"}}