Pay-per-call premium API access on Base 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 `/api/v1/keys/15` is listed as "Premium API Access" and costs up to $0.02 per call (maxAmountRequired of 20,000 base units of USDC with 6 decimals = $0.02). No API keys, rate limits, or subscriptions are required — each request is settled individually on-chain.
The broader platform advertises a suite of 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 the same $0.02/request price point.
However, the specific endpoint `/api/v1/keys/15` does not clearly map to any of the named API categories on the landing page. Its description is simply "Premium API Access," and no documentation, request/response schema, or usage examples are provided. The crawled /api, /pricing, and /README pages all returned only a "Connect wallet" prompt with no additional content. Without further documentation it is unclear what data or functionality this particular endpoint returns.
Capabilities
Use cases
- —Programmatic access to premium API services without subscription or API key management
- —Agent-driven workflows that need on-demand, per-call payment settlement
- —Testing x402 protocol integrations with a low-cost endpoint
Fit
Best for
- —Developers exploring x402 pay-per-request patterns
- —AI agents that need frictionless, keyless API access
- —Low-volume or sporadic API consumers who want to avoid 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
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/keys/15 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live (402 challenge captured) and pricing is clear ($0.02 USDC on Base), but there is no documentation, no request/response schema, no examples, and the purpose of this specific endpoint is ambiguous. The /api, /pricing, and /README pages returned no useful content.
Warnings
- —No documentation available — /api, /pricing, and /README pages only show 'Connect wallet' with no content.
- —The endpoint path /api/v1/keys/15 does not match any of the named APIs on the landing page; its actual functionality is unknown.
- —No request or response schema is provided; callers cannot know what to send or what to expect back.
- —No OpenAPI spec, ai-plugin manifest, or agents.txt found.
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/keys/15
- —All listed APIs are priced at $0.02/request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/keys/15