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 marketplace that exposes a broad set 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, settled in USDC on the Base network via the x402 protocol.
The specific endpoint `/api/v1/inbox/115` is listed as "Premium API Access" and returns a valid x402 402 challenge requesting up to 20,000 base units of USDC (0.02 USD, since USDC uses 6 decimals) on Base. Payment is made via the `exact` scheme to the specified wallet address. No API keys or rate limits are advertised; access is instant once payment is included in the X-PAYMENT header.
Documentation is minimal — the landing page lists available endpoints and pricing, but there is no OpenAPI spec, no request/response schema documentation, and no usage examples. The `/api`, `/pricing`, and `/README` pages all resolve to a "Connect wallet" prompt with no additional content. Because of this, the exact functionality behind `/api/v1/inbox/115` (as opposed to the other named endpoints) is unclear. Consumers should expect to experiment or contact the provider for details.
Capabilities
Use cases
- —Accessing AI inference (sentiment, summarization, classification, embeddings) on a per-call basis without API keys
- —Fetching real-time crypto token quotes and gas estimates via micropayment
- —Running geocoding or data validation requests with no subscription commitment
- —Exporting analytics data or generating insights reports on demand
Fit
Best for
- —Developers wanting zero-commitment, pay-per-use API access
- —AI agents that can settle x402 payments in USDC on Base
- —Prototyping and low-volume use cases where $0.02/call is cost-effective
Not for
- —High-volume production workloads needing guaranteed SLAs and detailed documentation
- —Users without a Base-compatible USDC wallet or x402 client
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/115 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Example
Request
{
"url": "https://lowpaymentfee.com/api/v1/inbox/115",
"body": {},
"method": "POST",
"headers": {
"X-PAYMENT": "<x402-payment-token>",
"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 a landing page listing, and the specific purpose of /api/v1/inbox/115 ('Premium API Access') is undefined. The /api, /pricing, and /README pages are empty. This is effectively a stub listing.
Warnings
- —No OpenAPI or schema documentation available for any endpoint
- —The specific purpose of /api/v1/inbox/115 is unclear — 'Premium API Access' is not described anywhere
- —All documentation pages (/api, /pricing, /README) resolve to a 'Connect wallet' prompt with no content
- —No response examples or error documentation available
- —Cannot verify what data or functionality is actually returned by this endpoint
Citations
- —All endpoints priced at $0.02/request with no API keys, no rate limits, instant access on Base networkhttps://lowpaymentfee.com
- —x402 challenge returns maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/inbox/115
- —Available categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com