x402-gated portfolio endpoint on Base, pay $0.02 per request in USDC — no API keys required.
What it does
This endpoint at lowpaymentfee.com exposes a portfolio resource at `/api/v1/portfolios/41` behind an x402 payment challenge. It is part of a broader platform offering data & analytics, AI/ML inference, finance/Web3, and infrastructure utility APIs, all priced at $0.02 per request and settled in USDC on the Base network.
The specific `/api/v1/portfolios/41` endpoint accepts POST requests and returns `application/json`. Payment is handled via the x402 protocol: callers receive a 402 challenge containing the accepted payment scheme (`exact`), the USDC asset contract on Base (`0x8335…`), and the maximum amount required of 20,000 base units (i.e., $0.02 given USDC's 6 decimals). No API keys, rate limits, or upfront commitments are advertised — access is purely pay-per-call.
Documentation beyond the landing page is extremely sparse. The `/docs`, `/api`, `/pricing`, and `/README` routes all returned only a "Connect wallet" prompt with no substantive content. There is no OpenAPI spec, no request/response schema documentation, and no description of what the "portfolios/41" resource actually contains or what POST body it expects. The endpoint is confirmed live (402 challenge captured), but without further documentation it is difficult to know what data or functionality it provides.
Capabilities
Use cases
- —Fetching portfolio data with per-request USDC micropayments
- —Agent-driven access to paid API endpoints without API key management
- —Programmatic portfolio queries settled on Base L2
Fit
Best for
- —Developers wanting keyless, pay-per-call API access
- —AI agents with x402-compatible wallets on Base
- —Users who prefer crypto micropayments over subscription billing
Not for
- —Users needing detailed API documentation or OpenAPI specs before integrating
- —High-volume consumers who need bulk/subscription pricing
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/41 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is zero documentation on what the portfolios/41 resource returns, what request body it expects, or what 'Premium API Access' actually provides. No OpenAPI spec, no examples, and all doc pages are blank beyond a wallet-connect prompt.
Warnings
- —No OpenAPI or schema documentation available — request and response formats are unknown.
- —All documentation pages (/docs, /api, /pricing, /README) returned only 'Connect wallet' with no content.
- —The specific purpose of /api/v1/portfolios/41 is undocumented; 'Premium API Access' is the only description.
- —The endpoint is listed under a generic platform with many diverse API categories; unclear if all are functional.
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units in USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/41
- —Platform advertises $0.02 per request, no API keys, no rate limits, instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/41
- —Documentation pages /docs, /api, /pricing, /README all show only 'Connect wallet'https://lowpaymentfee.com/docs