x402-gated portfolio endpoint on Base, pay $0.02 per request in USDC — no API keys needed.
What it does
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.
The 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.
Documentation 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.
Capabilities
Use cases
- —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
Fit
Best for
- —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
Not for
- —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
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/37 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
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 stub.
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.
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Base (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913).https://lowpaymentfee.com/api/v1/portfolios/37
- —The platform advertises $0.02 per request pricing with no API keys, no rate limits, and instant access on the Base network.https://lowpaymentfee.com
- —The platform offers APIs across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categories.https://lowpaymentfee.com