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/44` is listed as "Premium API Access" and costs up to $0.02 per call (20,000 base units of USDC with 6 decimals). No API keys, rate limits, or upfront commitments are required — callers simply attach an x402 payment header to 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 per-request pricing.
The `/api/v1/keys/44` endpoint itself is live and returns a proper 402 challenge with x402 version 1. However, the actual functionality behind this specific path ("Premium API Access") is not documented beyond its title — there is no OpenAPI schema, no request/response examples, and no detailed documentation available from the crawled pages. The broader site's /api, /pricing, and /README pages all returned only a "Connect wallet" prompt with no substantive content.
Capabilities
Use cases
- —Agents needing on-demand API access without subscription or API key management
- —Pay-per-call AI inference (sentiment, summarization, classification, embeddings)
- —Fetching real-time financial data (prices, exchange rates, gas estimates) with micropayments
- —Utility operations like geocoding, validation, and data conversion on a per-request basis
Fit
Best for
- —AI agents that need frictionless, keyless API access via x402
- —Developers prototyping with low-cost, no-commitment API calls
- —Applications requiring micropayment-settled data and AI endpoints on Base
Not for
- —High-volume production workloads needing guaranteed SLAs and detailed documentation
- —Users who need non-crypto payment methods or off-chain settlement
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/keys/44 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, but there is no OpenAPI schema, no request/response examples, and no documentation beyond a title. The specific functionality of /api/v1/keys/44 ('Premium API Access') is entirely undocumented. Most site pages returned only 'Connect wallet' with no content.
Warnings
- —No OpenAPI or schema documentation available for this endpoint
- —The specific purpose of /api/v1/keys/44 ('Premium API Access') is unclear — it may be a generic key or access token endpoint
- —Site documentation pages (/api, /pricing, /README) returned no useful content beyond 'Connect wallet'
- —No request or response examples are available; callers must discover behavior empirically
Citations
- —The endpoint returns a 402 challenge with x402 version 1, accepting USDC on Base with maxAmountRequired of 20000 base unitshttps://lowpaymentfee.com/api/v1/keys/44
- —All listed endpoints cost $0.02 per request with no API keys, rate limits, or minimumshttps://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 Base networkhttps://lowpaymentfee.com/api/v1/keys/44