Pay-per-call API platform on Base network via x402 — $0.02/request in USDC.
What it does
lowpaymentfee.com is a pay-per-request API platform that uses the x402 protocol to accept USDC payments on the Base network. The specific endpoint at `/api/v1/payments/331` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (0.02 USD) per call. No API keys or rate limits are required; callers simply attach an X-PAYMENT header with a valid x402 payment proof.
The broader platform advertises multiple API categories including Data & Analytics (metrics, reports, data export, insights), AI & Machine Learning (sentiment analysis, text 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 the same $0.02 per request price point.
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 the `/api/v1/payments/331` endpoint specifically returns. The endpoint is live and responds with a well-formed x402 challenge, but without documentation it is unclear what data or functionality this particular route provides.
Capabilities
Use cases
- —Accessing premium API data with per-request USDC micropayments on Base
- —Agent-driven API consumption without pre-registration or API keys
- —Testing x402 payment protocol integrations against a live endpoint
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents that need keyless, pay-as-you-go API access
- —Users who prefer crypto micropayments over subscription billing
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —Production workloads requiring SLA guarantees or support
- —Users without a Base network USDC wallet
Quick start
# The endpoint requires an x402 X-PAYMENT header with a valid payment proof.
# Without a payment library, you can probe the challenge:
curl -X POST https://lowpaymentfee.com/api/v1/payments/331
# Returns 402 with x402 challenge. Use an x402 client SDK to attach payment.Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but documentation is effectively nonexistent — all doc pages show only 'Connect wallet'. There is no OpenAPI schema, no request/response examples, and no explanation of what this specific endpoint returns. The listing is essentially a stub with confirmed liveness.
Warnings
- —No documentation available — all doc/pricing/API/README pages render only 'Connect wallet'
- —No OpenAPI or schema describing request parameters or response format
- —It is unclear what data or functionality /api/v1/payments/331 specifically provides
- —The platform lists many endpoint categories but none have documented schemas or examples
Citations
- —The endpoint returns a 402 challenge requesting up to 20,000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base networkhttps://lowpaymentfee.com/api/v1/payments/331
- —All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The platform offers APIs across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —Docs, API, pricing, and README pages all show only 'Connect wallet' with no further contenthttps://lowpaymentfee.com/docs