Pay-per-call API platform on Base network via x402 — $0.02/request in USDC, no API keys required.
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 utility services. All endpoints are priced at $0.02 per request, settled in USDC on the Base network. The x402 protocol means there are no API keys, no accounts, and no rate limits — callers simply attach a payment header to each request.
The specific endpoint at `/api/v1/products/43` is listed as "Premium API Access" and returns an x402 challenge requesting up to 20,000 base units of USDC (0.02 USD, since USDC uses 6 decimals) on Base. The payment is sent to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using the exact payment scheme. The endpoint accepts POST requests and returns `application/json`.
The broader platform advertises endpoints for sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and data generation — all at the same $0.02 price point. However, documentation beyond the landing page is extremely sparse (docs, pricing, and README pages all render only a "Connect wallet" prompt), so the actual functionality, request schemas, and response formats for this specific endpoint and others are not documented in any accessible way.
Capabilities
Use cases
- —Agents that need on-demand API access without pre-registration or API key management
- —Programmatic access to utility or data endpoints with per-call USDC micropayments
- —Testing x402 protocol integrations against a live endpoint
Fit
Best for
- —Developers exploring x402 payment protocol
- —AI agents needing keyless, pay-as-you-go API access
- —Low-volume consumers who want no subscription commitments
Not for
- —Users who need detailed API documentation or guaranteed SLAs
- —High-volume production workloads where per-call pricing is inefficient
- —Users without USDC on Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/products/43 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing. However, there is no documentation for request/response schemas, no OpenAPI spec, and the docs/pricing/README pages are all blank (just 'Connect wallet'). The purpose of this specific '/products/43' endpoint is unclear beyond the generic 'Premium API Access' label.
Warnings
- —No request or response schema documented — callers cannot know what to send or expect back
- —Documentation pages (/docs, /pricing, /README) are effectively empty
- —The specific purpose of /api/v1/products/43 ('Premium API Access') is not explained anywhere
- —No OpenAPI or machine-readable API specification available
Citations
- —All endpoints priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —x402 challenge requests maxAmountRequired of 20000 base units of USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/products/43
- —Platform offers endpoints across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com