Pay-per-call notification endpoint on Base via x402 — $0.02 per request in USDC.
What it does
This endpoint at `/api/v1/notifications/4` is part of the lowpaymentfee.com platform, which offers a suite of pay-per-request APIs spanning data & analytics, AI/ML inference, finance/Web3, and infrastructure utilities. All endpoints use the x402 payment protocol, settling in USDC on the Base network. The specific endpoint probed here is described as "Premium API Access" and accepts POST requests.
The x402 challenge confirms the endpoint is live and requires a maximum payment of 20,000 base units of USDC (0x8335…2913 on Base). Since USDC uses 6 decimals, this translates to $0.02 per request — consistent with the site's advertised flat pricing of $0.02/request across all endpoints. Payment is made to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout.
The platform advertises no API keys, no rate limits, and instant access. However, the actual behavior and response schema of the `/api/v1/notifications/4` endpoint are not documented — there is no OpenAPI spec, no example request/response, and the crawled docs and pricing pages returned only a wallet-connect prompt. The endpoint's purpose (what "notifications/4" delivers) is unclear from available material.
Capabilities
Use cases
- —Retrieving or triggering notifications via a pay-per-call model without API key management
- —Integrating low-cost per-request endpoints into agent workflows on Base
- —Testing x402 payment protocol integrations with a cheap live endpoint
Fit
Best for
- —Developers exploring x402 payment-gated APIs
- —Agents needing keyless, pay-per-use endpoint access
- —Low-volume consumers who want no subscription commitments
Not for
- —Users who need documented request/response schemas before integrating
- —High-volume consumers who would benefit from bulk pricing or subscriptions
- —Anyone needing non-USDC or non-Base payment settlement
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/notifications/4 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing. However, there is no OpenAPI spec, no documentation of request/response schemas, and the purpose of the /notifications/4 endpoint is entirely undocumented. The crawled pages beyond the landing page returned only wallet-connect prompts with no useful content.
Warnings
- —No OpenAPI or schema documentation available for this endpoint
- —The purpose and expected input/output of /api/v1/notifications/4 are undocumented
- —Crawled /api, /pricing, and /README pages returned no meaningful content
- —Cannot verify what data or functionality this specific endpoint provides
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/notifications/4
- —The platform advertises $0.02/request flat pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/notifications/4