Pay-per-request API platform on Base network via x402 — $0.02/call 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 `/api/v1/carts/11` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (i.e., $0.02) per call. The platform advertises no API keys, no rate limits, and instant access — you simply attach an x402 payment header to each request.
The broader platform offers endpoints across four categories: 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/request price point.
However, the specific endpoint being listed here (`/api/v1/carts/11`) does not clearly map to any of the documented API categories. Its description is simply "Premium API Access" with no further documentation on what data or functionality it returns. The docs, pricing, and API pages on the site all render only a "Connect wallet" prompt with no additional content, so there is no detailed schema or usage documentation available.
Capabilities
Use cases
- —Programmatic access to a pay-per-request API without needing API keys or subscriptions
- —Agent-driven workflows that need to purchase API calls with USDC on Base
- —Testing x402 payment flows with a low-cost endpoint
Fit
Best for
- —Developers exploring x402 payment protocol integrations
- —AI agents that need keyless, pay-as-you-go API access
- —Low-volume or sporadic API consumers who want no commitments
Not for
- —Users needing detailed API documentation or guaranteed SLAs
- —High-volume consumers who would benefit from bulk pricing or subscriptions
- —Anyone who needs to understand exactly what this specific endpoint returns before paying
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/carts/11 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, but there is no documentation on what this specific endpoint actually returns. The docs pages are empty (just 'Connect wallet'). No OpenAPI schema, no example responses, and the endpoint path '/api/v1/carts/11' doesn't match any of the documented API categories. Effectively a stub listing.
Warnings
- —The endpoint path /api/v1/carts/11 does not correspond to any of the documented API categories on the site — its actual functionality is unknown.
- —All documentation pages (docs, pricing, API, README) render only 'Connect wallet' with no useful content.
- —No OpenAPI schema or response examples are available; the output of this endpoint is entirely opaque.
- —The platform appears to be a demonstration or early-stage project — treat with caution.
Citations
- —The endpoint returns a 402 challenge requesting up to 20,000 base units of USDC ($0.02) on Base network.https://lowpaymentfee.com/api/v1/carts/11
- —The platform lists endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories, all at $0.02/request.https://lowpaymentfee.com
- —The platform advertises no API keys, no rate limits, instant access, and Base network settlement.https://lowpaymentfee.com
- —USDC contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 with 6 decimals.https://lowpaymentfee.com/api/v1/carts/11