x402-gated portfolio endpoint on Base, pay $0.02 per request in USDC — no API keys needed.
What it does
This endpoint at `/api/v1/portfolios/38` is part of the lowpaymentfee.com platform, which offers a collection of x402-protocol pay-per-request APIs spanning data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. The specific `/portfolios/38` resource is listed under "Premium API Access" but its exact data payload is not documented beyond the generic description. All endpoints on the platform share the same pricing model: $0.02 per request, settled in USDC on the Base network via the x402 payment protocol.
The platform advertises a no-friction model: no API keys, no rate limits, no subscriptions, and instant access. Callers send a POST request with an `X-PAYMENT` header containing a signed x402 payment proof. The x402 challenge confirms the endpoint is live, accepting USDC (contract `0x8335…2913` on Base) with a max amount of 20,000 base units (i.e., $0.02 given USDC's 6 decimals). The payment timeout is 300 seconds.
Documentation is extremely thin — 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 the `/portfolios/38` resource actually returns. The endpoint is confirmed live via the 402 challenge, but without documentation it is unclear what input the POST body expects or what shape the response takes.
Capabilities
Use cases
- —Fetching portfolio data (resource #38) via a single micropayment without account setup
- —Integrating pay-per-request data access into autonomous agents using x402
- —Demonstrating x402 payment protocol integration on Base
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents needing frictionless, keyless API access on Base
- —Low-volume, on-demand data retrieval without subscriptions
Not for
- —Users who need detailed API documentation or guaranteed SLAs
- —High-volume batch processing where per-request fees add up
- —Anyone requiring non-crypto payment methods
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/38 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is confirmed live via a valid x402 402 challenge, and pricing is clear ($0.02 USDC on Base). However, there is zero documentation on what the endpoint accepts or returns — docs pages are empty stubs. No OpenAPI schema, no examples, and the specific purpose of /portfolios/38 is undescribed.
Warnings
- —No documentation available — all doc/pricing/API pages render only 'Connect wallet' with no content
- —No OpenAPI or request/response schema provided; input and output formats are unknown
- —The specific purpose and data content of /portfolios/38 is not described anywhere
- —Cannot verify what data is actually returned without making a paid request
Citations
- —Platform charges $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —x402 challenge confirms USDC on Base with maxAmountRequired of 20000 base units (=$0.02) and 300s timeouthttps://lowpaymentfee.com/api/v1/portfolios/38
- —USDC asset contract on Base: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/38