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 `/api/v1/keys/19` 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; callers attach an X-PAYMENT header with each request.
The 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 listed endpoints share the same $0.02/request pricing. The site claims no rate limits and instant access.
Important caveat: the `/api/v1/keys/19` path does not clearly map to any of the named endpoints on the landing page. Its description is simply "Premium API Access," and no documentation, OpenAPI spec, or request/response schema was found beyond the x402 challenge. The crawled /api, /pricing, and /README pages all returned only a "Connect wallet" prompt with no additional content. Without documentation it is unclear what this specific endpoint actually returns.
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without subscriptions
- —Fetching real-time financial data such as token quotes, gas estimates, and exchange rates on a per-call basis
- —Running utility operations like geocoding, validation, and data conversion with micropayments
Fit
Best for
- —Agents or developers who want zero-signup, pay-as-you-go API access
- —Use cases requiring occasional or bursty API calls without committing to a subscription
- —Crypto-native workflows that can settle payments in USDC on Base
Not for
- —High-volume production workloads where per-call pricing may add up quickly
- —Users who need detailed API documentation, SLAs, or guaranteed uptime
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/keys/19 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The x402 challenge is live 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 specific endpoint's purpose is ambiguous. The /api, /pricing, and /README pages are empty behind a wallet gate.
Warnings
- —No OpenAPI or schema documentation available for this endpoint
- —The endpoint path /api/v1/keys/19 does not match any named endpoint on the landing page; its actual functionality is unknown
- —All documentation pages (/api, /pricing, /README) returned only 'Connect wallet' with no content
- —No example requests or responses are available to verify what the endpoint returns
Citations
- —The x402 challenge returns maxAmountRequired of 20000 in USDC (asset 0x8335…) on Base, equaling $0.02 per requesthttps://lowpaymentfee.com/api/v1/keys/19
- —The platform lists endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories all at $0.02/requesthttps://lowpaymentfee.com
- —The site advertises no API keys, no rate limits, instant access, and Base network settlementhttps://lowpaymentfee.com