{"id":"72c960ff-8833-4c2a-99e4-7d1bbc734794","shortId":"ctx2v9","kind":"x402","title":"Portfolio performance data via x402 micropayment on Base network, $0.02/request in USDC.","tagline":"Portfolio performance data via x402 micropayment on Base network, $0.02/request in USDC.","description":"This endpoint at lowpaymentfee.com provides portfolio performance data for a specific portfolio (ID 39) behind an x402 paywall. The endpoint accepts POST requests and returns JSON. Payment is settled on the Base network using USDC (contract 0x8335…2913) with a maximum cost of 20,000 base units, which equals $0.02 per request (USDC uses 6 decimals).\n\nThe provider lowpaymentfee.com hosts a broad catalog of x402-gated APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all priced at $0.02 per request. This particular endpoint falls under the finance category and appears to return performance metrics for a tracked portfolio. No API keys or rate limits are advertised; access is granted purely via the x402 payment header.\n\nDocumentation is extremely sparse. The docs, pricing, API, and README pages all render only a \"Connect wallet\" prompt with no substantive content. There is no OpenAPI schema, no request/response examples, and no description of what fields the portfolio performance response contains. The endpoint is confirmed live (returns a proper 402 challenge), but the lack of documentation means callers must discover the response format experimentally.","tags":[],"capabilities":["x402-payment","usdc-base-network","portfolio-performance","json-api","micropayment","no-api-key","pay-per-request"],"categories":["finance","data"],"synonyms":["portfolio analytics","investment performance","portfolio returns","financial data API","x402 finance","micropayment API","Base USDC API"],"warnings":["No API documentation available — docs, pricing, API, and README pages all show only 'Connect wallet' with no content","No OpenAPI or schema describing request parameters or response fields for this endpoint","The specific portfolio ID (39) is hardcoded in the path; it is unclear whether other portfolio IDs are available or what they represent","Response format and fields are completely unknown"],"endpointUrl":"https://lowpaymentfee.com/api/v1/portfolios/39/performance","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/39/performance","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.350","qualityRationale":"The endpoint is confirmed live with a valid x402 402 challenge, but documentation is essentially nonexistent — no OpenAPI spec, no request/response examples, no field descriptions. The portfolio endpoint path and pricing are clear, but everything else must be discovered 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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/39/performance","description":"Premium API 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data without API key management","Developers experimenting with x402 micropayment protocols on Base","Low-volume consumers who prefer pay-per-call over subscriptions"],"notFor":["Users needing detailed API documentation or response schema before integrating","High-frequency trading systems requiring sub-second latency guarantees","Anyone without a Base-network USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:00.222Z"},"updatedAt":"2026-04-27T22:33:20.902Z"}}