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/charges/221` is labeled "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 $0.02 per request.
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/charges/221` endpoint specifically returns. The endpoint is live (returns a valid 402 x402 challenge), but without documentation it is unclear what data or functionality this particular charge ID provides.
Capabilities
Use cases
- —Programmatic access to API services without managing API keys or subscriptions
- —Agent-driven workflows that need on-demand, per-call billing via crypto
- —Testing x402 protocol integrations with a low-cost endpoint
Fit
Best for
- —Developers exploring x402 payment protocol on Base
- —Agents needing keyless, pay-as-you-go API access
- —Low-volume consumers who want no subscription commitment
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume production workloads where per-call pricing at $0.02 may add up
- —Anyone without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/charges/221 \
-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 documentation is essentially nonexistent — every doc/pricing/API page shows only 'Connect wallet'. There is no OpenAPI schema, no request/response examples, and no explanation of what '/api/v1/charges/221' actually returns. The listing is effectively a stub with confirmed liveness and pricing.
Warnings
- —No documentation available — all doc pages render only 'Connect wallet'
- —No OpenAPI or schema describing request parameters or response format
- —The specific functionality of /api/v1/charges/221 ('Premium API Access') is undefined
- —No examples of request bodies or response payloads available
- —Cannot verify what data or service is actually delivered after payment
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/charges/221
- —Platform advertises $0.02/request pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset contract on Base: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/charges/221
- —Platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com