x402-gated Stripe invoice endpoint on Base, pay-per-call with USDC.

This endpoint at lowpaymentfee.com exposes a Stripe invoice resource (`/api/v1/stripe/invoices/166`) behind an x402 payment challenge. When called without payment, it returns a 402 with an x402 v1 challenge requiring USDC on the Base network. The maximum amount required is 20,000 base units of USDC (6 decimals), which equals $0.02 per request.

The parent site lowpaymentfee.com advertises a broad catalog of pay-per-call APIs spanning data & analytics, AI/ML (sentiment analysis, summarization, classification, embeddings), finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation). All endpoints are listed at $0.02 per request with no API keys, no rate limits, and no commitments — payment is handled entirely via the x402 protocol settling in USDC on Base.

This specific endpoint appears to serve Stripe invoice data (invoice ID 166). However, documentation is extremely sparse — the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no further technical detail. There is no OpenAPI schema, no request/response examples, and no description of what fields the invoice endpoint returns or what POST body it expects. The endpoint is confirmed live (402 challenge captured), but the lack of documentation makes it difficult to assess the actual utility or output format.