Pay-per-call notification endpoint on Base via x402 — $0.02 per request in USDC.
What it does
This endpoint at `/api/v1/notifications/21` is part of the lowpaymentfee.com platform, which offers a collection of pay-per-request APIs settled via the x402 protocol on the Base network using USDC. The specific endpoint is described as "Premium API Access" and accepts POST requests. Payment is $0.02 per call (20,000 base units of USDC with 6 decimals), settled on-chain to a specified wallet address. No API keys or rate limits are required — callers simply attach an X-PAYMENT header with the appropriate x402 payment proof.
The broader lowpaymentfee.com platform advertises endpoints across several 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 (geocoding, validation, conversion, generation). All endpoints are listed at $0.02 per request. However, this specific listing covers only the `/api/v1/notifications/21` endpoint, whose exact functionality beyond "Premium API Access" is not documented.
The endpoint is live and returned a proper 402 challenge when probed. The x402 challenge specifies scheme "exact", network "base", asset USDC (contract 0x8335…), and a max timeout of 300 seconds. No OpenAPI schema, detailed documentation, or example responses were found in the crawl.
Capabilities
Use cases
- —Sending or triggering notifications via a pay-per-call model without needing an API key
- —Integrating notification delivery into agent workflows that settle payments on Base
- —Testing x402 protocol integrations with a low-cost endpoint
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents needing keyless, pay-per-use notification endpoints
- —Low-volume notification use cases where $0.02/call is acceptable
Not for
- —High-volume notification systems where per-call costs would accumulate significantly
- —Users who need detailed documentation or guaranteed SLAs before integrating
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/notifications/21 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming it is operational. However, there is no documentation on what the notifications/21 endpoint actually does, no request/response schema, and no examples. The crawl pages beyond the homepage returned only 'Connect wallet' with no useful content. The endpoint's purpose is essentially unknown beyond its generic title.
Warnings
- —No documentation found for /api/v1/notifications/21 — its actual functionality is unknown
- —No request body schema or response schema available
- —No OpenAPI spec, README, or detailed docs were accessible from the crawl
- —The endpoint name 'Premium API Access' is generic and does not describe what it does
- —The platform lists many endpoint categories but none match a 'notifications' path, raising questions about this endpoint's purpose
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/notifications/21
- —All endpoints on the platform are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/notifications/21