Pay-per-request API platform on Base network via x402 — $0.02/call in USDC.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad catalog of pay-per-request endpoints across data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. All endpoints are priced at $0.02 per request, paid in USDC on the Base network, with no API keys, rate limits, or subscriptions required.
The specific endpoint `/api/v1/inbox/10` is listed as "Premium API Access" and accepts POST requests. Based on the x402 challenge, it charges up to 20,000 base units of USDC (0.02 USDC, i.e., $0.02) per call, settling to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 on Base. The broader platform advertises endpoints for sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, geocoding, validation, conversion, and data export — all at the same $0.02 price point.
Documentation is extremely sparse. The docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI schema, no request/response examples, and no description of what the `/api/v1/inbox/10` endpoint specifically returns or what input it expects beyond a POST with `application/json` content type. The platform is live (402 challenge confirmed), but without documentation it is difficult to know what data or functionality any given endpoint actually provides.
Capabilities
Use cases
- —Agents that need on-demand API access without managing API keys or subscriptions
- —Programmatic access to AI inference (sentiment, summarization, classification, embeddings) at micro-payment scale
- —Fetching real-time finance data (prices, exchange rates, gas estimates) with per-call USDC payment
- —Geocoding, validation, and data conversion utilities paid per request
Fit
Best for
- —AI agents with x402-compatible wallets on Base
- —Developers wanting zero-commitment, pay-as-you-go API access
- —Low-volume or bursty workloads where subscription pricing is wasteful
Not for
- —High-volume production workloads needing SLAs or guaranteed uptime documentation
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —Anyone without a Base-network USDC wallet
Quick start
# x402 POST to the Premium API Access endpoint
curl -X POST https://lowpaymentfee.com/api/v1/inbox/10 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but documentation is essentially nonexistent — every doc page shows only 'Connect wallet'. There is no OpenAPI schema, no request/response examples, and no explanation of what '/api/v1/inbox/10' actually does. The listing is effectively a stub.
Warnings
- —No documentation available — all doc pages render only 'Connect wallet'
- —No OpenAPI or schema describing request/response formats for any endpoint
- —The specific purpose of /api/v1/inbox/10 ('Premium API Access') is unexplained
- —Cannot verify what data or functionality any endpoint actually returns
- —The broad catalog of endpoints (AI, finance, geo, etc.) is listed on the homepage but none have documented behavior
Citations
- —All endpoints priced at $0.02 per request with no API keys, rate limits, or minimumshttps://lowpaymentfee.com
- —x402 challenge returns maxAmountRequired of 20000 base units of USDC (USD Coin, 6 decimals = $0.02) on Base networkhttps://lowpaymentfee.com/api/v1/inbox/10
- —Platform offers endpoints across Data & Analytics, AI & ML, 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