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 settled in USDC on the Base network. The specific endpoint at `/api/v1/keys/30` is listed as "Premium API Access" and costs up to $0.02 per call (20,000 base units of USDC with 6 decimals). Payment is handled via the x402 protocol — no API keys, accounts, or subscriptions are required; each request is paid for individually with an on-chain USDC transaction.
The wider platform advertises four endpoint 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 functionality behind the `/api/v1/keys/30` endpoint is not documented beyond its "Premium API Access" label. There is no OpenAPI schema, no request/response examples, and the crawled docs pages (pricing, README, API) all resolve to a minimal "Connect wallet" prompt with no additional detail. The endpoint is confirmed live — it returns a valid x402 402 challenge — but what it actually returns upon successful payment is unknown from available materials.
Capabilities
Use cases
- —Agents that need on-demand API access without managing API keys or subscriptions
- —Paying for individual AI inference calls (sentiment, summarization, classification, embeddings) with USDC
- —Fetching financial data like token quotes, gas estimates, or exchange rates per request
- —Running utility operations like geocoding or data validation with per-call billing
Fit
Best for
- —AI agents with USDC on Base that need frictionless, keyless API access
- —Developers prototyping integrations who want zero-commitment pay-per-use pricing
- —Web3-native applications that prefer on-chain settlement over traditional billing
Not for
- —High-volume production workloads where $0.02/request adds up significantly
- —Users who need detailed API documentation and guaranteed SLAs before integrating
- —Anyone without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/keys/30 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is confirmed live with a valid x402 402 challenge, but there is no OpenAPI schema, no request/response examples, and no documentation explaining what the /api/v1/keys/30 endpoint actually returns. The crawled pages beyond the homepage are empty stubs. The listing is essentially a stub with pricing info only.
Warnings
- —No documentation available for what /api/v1/keys/30 actually returns upon successful payment
- —No OpenAPI or schema definition found for any endpoint on the platform
- —Crawled docs/pricing/README pages all resolve to a minimal 'Connect wallet' page with no content
- —The purpose of 'Premium API Access' is ambiguous — it may be an API key generator or a meta-endpoint rather than a data endpoint
Citations
- —The endpoint returns a valid x402 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/keys/30
- —All listed endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The platform offers endpoints in four categories: Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/keys/30