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 variety 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 priced at $0.02 per request, payable in USDC on the Base network via the x402 protocol.
The specific endpoint at `/api/v1/invoices/27` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. Payment is made via the x402 exact scheme with a 300-second timeout. No API keys or rate limits are advertised; access is instant upon payment.
Documentation is extremely sparse — the /docs, /pricing, /api, and /README pages all render only a "Connect wallet" prompt with no substantive content. There is no OpenAPI schema, no request/response examples, and no detailed documentation for any endpoint. The exact functionality behind the `/api/v1/invoices/27` path is unclear; the name "Premium API Access" does not describe a specific capability. The platform appears to be a demonstration or early-stage deployment of x402 pay-per-call APIs.
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API keys
- —Fetching real-time financial data like token quotes, exchange rates, and gas estimates
- —Running utility operations like geocoding, validation, and data conversion on a per-call basis
- —Demonstrating or testing x402 payment protocol integrations
Fit
Best for
- —Developers experimenting with x402 pay-per-call protocols
- —Agents needing low-cost, keyless API access on Base
- —Projects requiring diverse lightweight API endpoints without subscription commitments
Not for
- —Production workloads requiring documented SLAs and detailed API schemas
- —Users who need high-throughput or bulk data access at volume discounts
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/invoices/27 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming it accepts USDC on Base at $0.02. However, there is no OpenAPI schema, no request/response examples, and all documentation pages are empty stubs. The specific purpose of /api/v1/invoices/27 is unclear beyond the generic label 'Premium API Access'.
Warnings
- —Documentation pages (/docs, /pricing, /api, /README) all render only 'Connect wallet' with no usable content
- —No OpenAPI or JSON schema available for any endpoint
- —The specific functionality of /api/v1/invoices/27 ('Premium API Access') is not documented — it may be a generic or demo endpoint
- —No request body schema or response format is documented anywhere
- —Platform may be early-stage or a demonstration site
Citations
- —All endpoints priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —x402 challenge returns maxAmountRequired of 20000 base units of USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base, equaling $0.02https://lowpaymentfee.com/api/v1/invoices/27
- —Platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com