x402-gated portfolio endpoint on Base, pay-per-request with USDC.
What it does
This endpoint at `/api/v1/portfolios/70` 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 data, and infrastructure utilities. The specific `/portfolios/70` resource is listed under "Premium API Access" but its exact response payload is undocumented — no OpenAPI schema, example responses, or detailed docs were found in the crawl. The platform advertises a uniform $0.02-per-request pricing model, though the x402 challenge for this particular endpoint shows a `maxAmountRequired` of 20,000 base units of USDC (0x8335… on Base), which equals $0.02 given USDC's 6 decimals.
Payment is handled entirely via the x402 protocol: callers attach an `X-PAYMENT` header with a signed payment proof; no API keys or accounts are needed. The endpoint accepts POST requests and settles on the Base L2 network. The site claims no rate limits and instant access. However, documentation is extremely thin — the /docs, /pricing, /api, and /README pages all returned only a "Connect wallet" prompt with no substantive content. Without knowing what data `/portfolios/70` actually returns, callers should treat this as an exploratory integration.
Capabilities
Use cases
- —Fetching portfolio data behind a per-request USDC micropayment wall
- —Integrating x402-compatible agents with pay-as-you-go data endpoints
- —Exploring x402 protocol payment flows on Base L2
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents that can sign USDC payments on Base
- —Use cases needing keyless, pay-per-call API access
Not for
- —Users who need detailed API documentation or guaranteed SLAs
- —Applications requiring free or subscription-based access
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/70 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <signed-x402-payment-proof>"Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02/request in USDC on Base), but there is no documentation, no OpenAPI schema, no example request/response, and the purpose of '/portfolios/70' is not explained anywhere. The docs pages are empty stubs. This is effectively a stub listing.
Warnings
- —No documentation available — /docs, /pricing, /api, and /README all return only a wallet-connect prompt with no content.
- —The exact data returned by /api/v1/portfolios/70 is unknown; 'Premium API Access' is the only description provided.
- —No OpenAPI spec or output schema beyond the x402 challenge metadata.
- —The platform lists many endpoints but none appear individually documented.
Citations
- —The x402 challenge returns maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/portfolios/70
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/70
- —Platform advertises $0.02/request pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —Documentation pages (/docs, /pricing, /api, /README) contain only a 'Connect wallet' prompthttps://lowpaymentfee.com/docs