Pay-per-call API platform on Base (USDC) covering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad catalog of pay-per-request endpoints settled in USDC on the Base network. The specific endpoint at `/api/v1/inbox/191` is listed as "Premium API Access" and costs up to $0.02 per call (20,000 base units of USDC with 6 decimals). Payment is handled via the x402 protocol — no API keys, no subscriptions, no rate limits. You send a POST request with an `X-PAYMENT` header containing a signed payment proof, and the endpoint returns its response.
The broader 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 endpoints are listed at the same $0.02/request price point.
However, the specific endpoint probed here (`/api/v1/inbox/191`) does not clearly map to any of the advertised categories. Its description is simply "Premium API Access" with no further documentation on what it actually returns. There is no OpenAPI spec, no request/response schema documentation, and the crawled docs pages (pricing, README, API) all resolve to a minimal "Connect wallet" page with no additional content. Without knowing what this endpoint does, callers should treat it as an opaque paid endpoint until more documentation surfaces.
Capabilities
Use cases
- —Programmatic access to paid API endpoints without traditional API key management
- —Agent-driven workflows that need to pay for API calls on-the-fly using USDC on Base
- —Accessing data, AI, finance, or utility services via micropayments
Fit
Best for
- —Developers or agents with USDC on Base who want frictionless pay-per-call access
- —Scenarios where avoiding API key signup and subscription commitments is valuable
- —Low-volume or sporadic API usage where per-request pricing is cost-effective
Not for
- —Users who need detailed documentation or guaranteed SLAs before integrating
- —High-volume consumers who would benefit from bulk pricing or subscription plans
- —Anyone without a Base-compatible wallet or USDC holdings
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/191 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <signed-x402-payment-proof>" \
-d '{}'Endpoint
Quality
The endpoint is live (returns a valid 402 x402 challenge) and pricing is clear ($0.02 USDC on Base), but there is zero documentation on what this specific endpoint does, no request/response schema, and the crawled pages beyond the landing page are empty. The endpoint path '/api/v1/inbox/191' doesn't match any of the advertised API categories, making its purpose unknown.
Warnings
- —No documentation exists for what /api/v1/inbox/191 actually returns — 'Premium API Access' is the only description
- —No OpenAPI spec, no request schema, no response schema available
- —The /api, /pricing, and /README pages all resolve to a minimal 'Connect wallet' page with no useful content
- —The endpoint path does not match any of the advertised API categories on the landing page
- —Purpose and functionality of this specific endpoint are entirely unknown
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/inbox/191
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/inbox/191
- —Platform advertises $0.02/request pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —Four endpoint categories are listed: Data & Analytics, AI & Machine Learning, Finance & Web3, Infrastructurehttps://lowpaymentfee.com