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 (`/api/v1/portfolios/6`) 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. No API keys, accounts, or rate limits are advertised — callers simply attach an x402 payment header to each request.
The specific `/api/v1/portfolios/6` endpoint accepts POST requests and returns `application/json`. The x402 challenge advertises a `maxAmountRequired` of 20,000 base units of USDC (contract `0x8335…2913` on Base, 6 decimals), which equals $0.02. Payment is sent to `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using the "exact" scheme with a 300-second timeout.
Documentation on the site is extremely thin — the docs, pricing, API, and README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no request/response schema, and no explanation of what the portfolios resource actually returns or what POST body it expects. The endpoint is confirmed live (402 challenge captured), but without documentation it is difficult to know what data or functionality it provides beyond its name.
Capabilities
Use cases
- —Retrieving portfolio data without needing an API key or subscription
- —Agent-driven portfolio lookups with automatic per-call USDC micropayments
- —Integrating pay-per-request financial data into automated workflows
Fit
Best for
- —Developers wanting zero-signup, pay-per-call portfolio data
- —AI agents that can settle x402 payments on Base
- —Prototyping financial data integrations without committing to a subscription
Not for
- —Users who need detailed API documentation or request/response schemas before integrating
- —High-volume consumers who need bulk pricing or rate-limit guarantees
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/portfolios/6 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is confirmed live with a valid x402 402 challenge, and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond the endpoint name, and no examples. The docs pages are empty. The purpose of the portfolios resource is unknown.
Warnings
- —No API documentation available — docs, pricing, API, and README pages all show only 'Connect wallet' with no content.
- —No request body schema or response schema provided; callers cannot know what to send or what to expect.
- —The specific purpose and data returned by /api/v1/portfolios/6 is undocumented and unclear.
- —This endpoint is not listed on the provider's own homepage catalog of available APIs, raising questions about its status.
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/portfolios/6
- —All APIs on the platform are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/portfolios/6