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 hosts a collection of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and general utility services. Every endpoint is priced at $0.02 per request, paid in USDC on the Base network via the x402 protocol. There are no API keys, no rate limits, and no upfront commitments — callers simply attach an x402 payment header to each request.
The specific endpoint at `/api/v1/inbox/124` is listed as "Premium API Access" and returns a 402 challenge requesting up to 20,000 base units of USDC (0.02 USD, since USDC uses 6 decimals) on Base. The payment is settled to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using the exact-amount scheme. The endpoint accepts POST requests and returns `application/json`.
Note that while the landing page advertises many endpoint categories (sentiment analysis, text summarization, embeddings, price feeds, geocoding, etc.), the crawled documentation is extremely thin — the /api, /pricing, and /README pages all resolve to a "Connect wallet" stub with no further detail. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available. The actual functionality behind `/api/v1/inbox/124` specifically is unclear from the available material; the name "Premium API Access" is generic and does not describe a concrete capability.
Capabilities
Use cases
- —Programmatic access to pay-per-call API services without API key management
- —Agent-driven workflows that need on-demand API calls settled in USDC on Base
- —Testing x402 payment flows against a live endpoint
Fit
Best for
- —Developers exploring x402 payment protocol integrations
- —Agents needing 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 guaranteed SLAs
- —High-volume production workloads requiring rate-limit guarantees or bulk pricing
- —Anyone needing non-USDC or non-Base payment options
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/124 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>" \
-d '{}'Example
Request
{}Endpoint
Quality
The endpoint is live and returns a valid 402 challenge, but there is no OpenAPI spec, no request/response schema, no documentation beyond a landing page listing, and the specific purpose of /api/v1/inbox/124 ('Premium API Access') is entirely opaque. Effectively a stub listing.
Warnings
- —No OpenAPI or schema documentation available for any endpoint
- —The /api, /pricing, and /README pages are empty stubs ('Connect wallet' only)
- —The specific functionality of /api/v1/inbox/124 is undocumented — 'Premium API Access' is a generic label
- —No request body schema or response schema is documented anywhere
- —Cannot verify what data or service is actually returned upon successful payment
Citations
- —All endpoints priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —402 challenge requests maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/inbox/124
- —Platform lists endpoints across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com