x402-gated premium API endpoint on Base, pay-per-request with USDC.
What it does
This endpoint at `/api/v1/portfolios/78` is part of the lowpaymentfee.com platform, which offers a collection of x402-protocol pay-per-call APIs spanning data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. The specific `/portfolios/78` resource is listed under "Premium API Access" and accepts POST requests, returning JSON responses. Payment is settled on the Base network using USDC (contract 0x8335…2913) via the x402 exact-payment scheme.
The x402 challenge advertises a `maxAmountRequired` of 20,000 base units. Since USDC uses 6 decimals, this converts to $0.02 per request — consistent with the site's uniform $0.02/request pricing across all endpoints. The platform emphasizes simplicity: no API keys, no rate limits, no commitments, and instant access. You send a POST with the x402 payment header and receive the response directly.
However, the crawled documentation pages (`/docs`, `/api`, `/pricing`, `/README`) all returned only a "Connect wallet" prompt with no substantive content. There is no OpenAPI schema, no request/response examples, and no documentation describing what the `/portfolios/78` endpoint actually returns or what input it expects. The endpoint name "Premium API Access" is generic and does not clarify the data or functionality provided. Without documentation, the actual utility of this specific endpoint remains unclear.
Capabilities
Use cases
- —Fetching portfolio data via a single paid API call
- —Integrating pay-per-request data access into agent workflows
- —Accessing premium content without API key registration
Fit
Best for
- —Agents that can settle x402 payments on Base with USDC
- —Developers wanting zero-signup, pay-as-you-go API access
- —Micropayment-based data retrieval without subscriptions
Not for
- —Users needing detailed API documentation or schemas before integration
- —High-volume use cases where per-request pricing may add up
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/78 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing ($0.02 USDC on Base). However, there is no documentation, no OpenAPI schema, no request/response examples, and the endpoint's actual functionality ('Premium API Access' for '/portfolios/78') is entirely opaque. All doc pages returned only 'Connect wallet' with no content.
Warnings
- —No documentation available — all doc pages (/docs, /api, /pricing, /README) returned only 'Connect wallet'
- —No OpenAPI or schema describing request parameters or response format
- —The purpose and data returned by /api/v1/portfolios/78 is unknown — 'Premium API Access' is a generic label
- —Cannot verify what data or service this endpoint actually provides
Citations
- —The x402 challenge advertises maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/78
- —USDC contract address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/portfolios/78
- —Platform pricing is $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —Documentation pages returned only 'Connect wallet' with no substantive contenthttps://lowpaymentfee.com/docs