Pay-per-call API platform on Base (USDC) offering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-enabled API platform that provides a broad catalog of pay-per-request 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 priced at $0.02 per request, paid in USDC on the Base network via the x402 protocol.
The specific endpoint `/api/v1/keys/23` is listed as "Premium API Access" and carries a maximum charge of 20,000 base units of USDC (0.02 USDC, i.e., $0.02) per call. Payment is settled on-chain to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using the USDC contract on Base (`0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`). No API keys or rate limits are advertised; access is gated purely by the x402 payment header. The endpoint accepts POST requests and returns `application/json`.
Documentation beyond the landing page is sparse — the /api, /pricing, and /README pages all resolve to a "Connect wallet" prompt with no additional technical detail. There is no OpenAPI spec, no request/response schema documentation, and no examples of what the `/api/v1/keys/23` endpoint actually returns. The name "Premium API Access" and its path (`/keys/23`) suggest it may return or provision an API key or access token, but this is speculative.
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key signup
- —Fetching real-time crypto price feeds, exchange rates, and gas estimates on a per-call basis
- —Running data analytics queries and exporting reports with micropayments
- —Using utility services like geocoding and data validation without subscriptions
Fit
Best for
- —Agents or developers who want instant, keyless API access via crypto micropayments
- —Low-volume or sporadic API consumers who prefer pay-per-use over subscriptions
- —Web3-native applications that can settle USDC payments on Base
Not for
- —High-volume production workloads where per-call crypto settlement adds latency and overhead
- —Users without a Base-compatible wallet or USDC holdings
- —Developers who need detailed API documentation, SDKs, or guaranteed SLAs
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/keys/23 \
-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 OpenAPI spec, no request/response schema, no documentation beyond a landing page listing, and the purpose of /api/v1/keys/23 specifically is unclear. Effectively a stub listing.
Warnings
- —No OpenAPI or schema documentation available — request and response formats are unknown
- —The /api, /pricing, and /README pages all return only a 'Connect wallet' prompt with no useful content
- —The exact purpose of /api/v1/keys/23 ('Premium API Access') is unclear — it may provision keys or tokens but this is unconfirmed
- —No examples of successful responses are available
Citations
- —All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The endpoint /api/v1/keys/23 returns a 402 challenge requiring 20,000 base units of USDC (USD Coin) on Base networkhttps://lowpaymentfee.com/api/v1/keys/23
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/keys/23