Pay-per-call premium API access on Base via x402 — $0.02/request in USDC.
What it does
This endpoint at lowpaymentfee.com provides "Premium API Access" via the x402 payment protocol. The specific path `/api/v1/inbox/173` is one of many endpoints offered by the provider, which advertises a broad catalog spanning data & analytics, AI & machine learning (sentiment analysis, 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, payable in USDC on the Base network with no API keys, no rate limits, and no minimum commitments.
The x402 challenge for this specific endpoint confirms it is live, accepting POST requests, and requires a maximum payment of 20,000 base units of USDC (0x8335…2913 on Base). Since USDC uses 6 decimals, this equals $0.02 per call. Payment is made via the x402 "exact" scheme to the specified payTo address, with a 300-second timeout window.
However, the exact functionality behind `/api/v1/inbox/173` is not documented beyond the generic label "Premium API Access." The provider's landing page lists many other endpoints but does not describe this specific inbox path. There is no OpenAPI spec, no request/response schema documentation, and the pricing, README, and API pages behind the site require a wallet connection to view. Prospective callers should be aware that the actual behavior of this particular endpoint is unclear from available documentation.
Capabilities
Use cases
- —Programmatic access to a pay-per-call API without needing API keys or subscriptions
- —Agent-driven workflows that need to pay for API calls on-the-fly using USDC on Base
- —Testing x402 payment protocol integrations with a low-cost endpoint
Fit
Best for
- —Developers exploring x402 payment-gated APIs
- —AI agents that can settle micropayments in USDC on Base
- —Users who want no-commitment, no-signup API access
Not for
- —Users who need detailed documentation or guaranteed SLAs before calling
- —Anyone who cannot transact in USDC on the Base network
- —High-volume batch workloads where $0.02/request adds up quickly
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/173 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but the specific functionality of /api/v1/inbox/173 is undocumented. There is no OpenAPI spec, no request/response schema, and no examples. The provider's site lists many endpoints but does not describe this one. Effectively a stub listing.
Warnings
- —The exact functionality of /api/v1/inbox/173 is not documented — 'Premium API Access' is a generic label
- —No OpenAPI spec or request/response schema available
- —Pricing, README, and API documentation pages require wallet connection and returned no useful content
- —The provider lists many diverse endpoints; it is unclear whether all are fully implemented
Citations
- —The provider lists endpoints across data & analytics, AI/ML, finance/Web3, and infrastructure categories, all priced at $0.02/requesthttps://lowpaymentfee.com
- —The site advertises no API keys, no rate limits, instant access, and Base network settlementhttps://lowpaymentfee.com
- —x402 challenge confirms maxAmountRequired of 20000 base units of USDC (6 decimals = $0.02) on Base networkhttps://lowpaymentfee.com/api/v1/inbox/173