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/charges/139` is listed as "Premium API Access" and costs $0.02 per call (20,000 base units of USDC with 6 decimals). No API keys, accounts, or rate limits are advertised — callers simply attach an X-PAYMENT header with a valid x402 payment proof to access the resource.
The broader platform advertises multiple API categories including 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 probed (`/api/v1/charges/139`) does not clearly map to any of the named API categories on the landing page. Its description is simply "Premium API Access" with no further documentation on what data or functionality it returns. The docs, pricing, and API pages all rendered only a "Connect wallet" prompt with no substantive content. Without documentation or example responses, it is unclear what payload this endpoint returns upon successful payment.
Capabilities
Use cases
- —Programmatic access to a pay-per-call API without needing API keys or subscriptions
- —Agent-driven workflows that settle per-request costs in USDC on Base
- —Testing x402 protocol integrations with a low-cost endpoint
Fit
Best for
- —Developers exploring x402 payment protocol integrations
- —Agents that need keyless, on-demand API access settled in USDC
- —Low-volume or sporadic API consumers who prefer pay-per-use over subscriptions
Not for
- —Users who need detailed API documentation or guaranteed SLAs before purchasing
- —High-volume consumers who would benefit from bulk pricing or rate-limited plans
- —Anyone without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/charges/139 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live (402 challenge captured) and pricing is clear ($0.02 USDC on Base), but there is no documentation, no OpenAPI schema, no example request/response, and the specific endpoint's purpose is undescribed beyond the generic label 'Premium API Access'. The docs/pricing/API pages all returned only 'Connect wallet' with no content.
Warnings
- —No documentation available — docs, pricing, and API pages all render only 'Connect wallet'
- —The endpoint /api/v1/charges/139 does not correspond to any named API on the landing page; its actual functionality is unknown
- —No OpenAPI schema, no example requests or responses provided
- —No information on uptime, SLAs, or data sources
Citations
- —The endpoint returns a 402 challenge requesting 20,000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base networkhttps://lowpaymentfee.com/api/v1/charges/139
- —All listed APIs are priced at $0.02/request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —Platform advertises categories: Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com