Pay-per-call API platform on Base (USDC) via x402 — $0.02/request, no API keys required.
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/payments/321` is listed as "Premium API Access" and charges 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 uniformly priced at $0.02 per request.
This particular endpoint (`/api/v1/payments/321`) is confirmed live, returning a proper 402 challenge with x402 version 1. The payment is settled on-chain to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using USDC (`0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`) on Base. The timeout for payment is 300 seconds. However, documentation is extremely thin — the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no additional technical detail, so the actual request/response schemas for this endpoint are unknown.
Capabilities
Use cases
- —Agents that need to make authenticated API calls without managing API keys
- —Programmatic access to premium data or services with per-request crypto payments
- —Testing x402 protocol integrations with a low-cost live endpoint
- —Paying for API access directly from a crypto wallet on Base
Fit
Best for
- —Developers or agents wanting key-free, pay-as-you-go API access
- —x402 protocol experimentation at low cost ($0.02/call)
- —Scenarios where traditional API key management is undesirable
Not for
- —Users who need detailed API documentation or well-defined request/response schemas
- —High-volume use cases where per-request payment overhead is impractical
- —Users without access to USDC on the Base network
Quick start
# Send a POST with an x402 payment header (USDC on Base)
curl -X POST https://lowpaymentfee.com/api/v1/payments/321 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is confirmed live with a valid 402 challenge and clear pricing ($0.02 USDC on Base). However, there is no OpenAPI schema, no documentation beyond a landing page listing, no request/response examples, and all doc pages render only 'Connect wallet'. The actual functionality behind 'Premium API Access' at /api/v1/payments/321 is undefined.
Warnings
- —No API documentation available — docs, pricing, API, and README pages all show only 'Connect wallet'
- —The purpose and expected input/output of /api/v1/payments/321 ('Premium API Access') is not documented anywhere
- —No OpenAPI spec or request/response schema provided
- —The endpoint name 'Premium API Access' is generic and does not describe what the endpoint actually does
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/payments/321
- —All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/payments/321
- —Platform offers endpoints in Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com