Pay-per-request API platform on Base network via x402 — $0.02/call in USDC.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad catalog of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and utility services. Every endpoint costs $0.02 per request, paid in USDC on the Base network with no API keys, no rate limits, and no subscriptions required. The x402 payment protocol handles authentication: callers include an X-PAYMENT header with a signed USDC payment, and the server fulfills the request upon verification.
The specific endpoint at `/api/v1/invoices/48` is listed as "Premium API Access" and returns `application/json`. Its x402 challenge advertises a maxAmountRequired of 20,000 base units of USDC (0x8335… on Base), which equals $0.02 given USDC's 6 decimals. The endpoint accepts POST requests and is discoverable. The broader platform advertises categories including metrics, reports, data export, insights, sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and generation — all at the same $0.02 price point.
Documentation is extremely sparse: the /docs, /pricing, /api, and /README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawl. The actual functionality behind each endpoint is unclear beyond the category labels on the landing page.
Capabilities
Use cases
- —Accessing data analytics and reports without subscription or API key management
- —Running AI inference tasks (sentiment, summarization, classification, embeddings) with per-call USDC payments
- —Fetching real-time crypto and finance data (prices, exchange rates, gas estimates) via micropayments
- —Using utility services (geocoding, validation, conversion) on a pay-as-you-go basis
Fit
Best for
- —Developers who want zero-friction API access without signup or API keys
- —Agents and bots that can settle payments programmatically via x402 on Base
- —Low-volume or sporadic API consumers who prefer per-call pricing over subscriptions
Not for
- —High-volume production workloads where $0.02/request adds up significantly
- —Users who need detailed API documentation, SDKs, or guaranteed SLAs
- —Developers without a Base-network USDC wallet or x402 client
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/invoices/48 \
-H "X-PAYMENT: <x402-signed-payment-header>" \
-H "Content-Type: application/json"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond category labels, and no examples. The actual functionality of /api/v1/invoices/48 is entirely opaque — 'Premium API Access' is not descriptive. The docs pages are empty.
Warnings
- —No OpenAPI spec or request/response schema available
- —All documentation pages (/docs, /pricing, /api, /README) render only 'Connect wallet' with no content
- —The specific endpoint /api/v1/invoices/48 has no description of what it actually does beyond 'Premium API Access'
- —Cannot verify what data or service any endpoint actually returns without paying
- —Platform appears to be a demo or early-stage project with placeholder documentation
Citations
- —All endpoints cost $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The x402 challenge for /api/v1/invoices/48 advertises maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/invoices/48
- —Platform offers endpoints across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —Documentation pages render only a 'Connect wallet' prompt with no further contenthttps://lowpaymentfee.com/docs