Pay-per-request API suite on Base via x402 — data, AI, finance, and utility endpoints at $0.02/call.
What it does
lowpaymentfee.com hosts a collection of pay-per-request API endpoints settled via the x402 protocol on the Base network using USDC. The specific endpoint `/api/v1/products/3` is labeled "Premium API Access" and requires a payment of up to 20,000 base units of USDC (0.02 USD, since USDC uses 6 decimals) per call. No API keys or rate limits are advertised — callers simply attach an X-PAYMENT header with a valid x402 payment proof.
The broader platform offers 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 listed at the same $0.02/request price point and settle on Base via USDC to the same payTo address.
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 `/api/v1/products/3` endpoint itself is live (returns a proper 402 challenge), but without documentation it is unclear what data or functionality it actually returns upon successful payment.
Capabilities
Use cases
- —Accessing premium API data with per-request USDC micropayments on Base
- —Agent-driven API consumption without pre-registration or API keys
- —Testing x402 payment flows against a live endpoint
Fit
Best for
- —Developers experimenting with x402 protocol payments
- —Agents that need keyless, pay-as-you-go API access on Base
- —Low-volume consumers who want no subscription commitments
Not for
- —Users who need detailed API documentation or schemas before integrating
- —High-volume production workloads requiring SLAs or guaranteed uptime
- —Users without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/products/3 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, but there is zero documentation on what the endpoint actually returns, no OpenAPI spec, no request/response examples, and all doc pages are empty. The listing is effectively a stub with confirmed liveness.
Warnings
- —No documentation available — /docs, /pricing, /api, and /README all render only 'Connect wallet' with no content
- —No OpenAPI or schema definition found for any endpoint
- —The specific functionality of /api/v1/products/3 ('Premium API Access') is completely undocumented — unclear what data it returns
- —No request body schema or response schema available
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/products/3
- —All endpoints are priced at $0.02/request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/products/3