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/116` is one of many endpoints offered by the provider, which hosts a broad catalog spanning data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities — all priced at $0.02 per request paid in USDC on the Base network.
The x402 challenge confirms the endpoint is live and accepts POST requests. Payment is settled on-chain using USDC (contract 0x8335…2913 on Base) with a maximum amount of 20,000 base units, which equals $0.02 (USDC uses 6 decimals). No API keys are required; callers simply attach an X-PAYMENT header with a valid x402 payment proof. The provider advertises no rate limits and instant access.
However, the specific functionality behind `/api/v1/inbox/116` is not documented on the provider's landing page — it does not appear in any of the listed API categories. The landing page catalogs endpoints like sentiment analysis, text summarization, price feeds, geocoding, and more, but "inbox/116" is not among them. Without further documentation or an OpenAPI spec, the exact input/output behavior of this particular endpoint is unknown. Callers should treat this as an opaque premium endpoint until more documentation surfaces.
Capabilities
Use cases
- —Programmatic access to a premium API endpoint with per-request USDC micropayments
- —Agent-driven workflows that need keyless, on-demand API calls settled on Base
- —Testing x402 payment protocol integrations against a live endpoint
Fit
Best for
- —Developers experimenting with x402 payment-gated APIs
- —AI agents that can settle USDC payments on Base autonomously
- —Users who want pay-as-you-go access without subscriptions or API keys
Not for
- —Users who need clearly documented input/output schemas before calling
- —Anyone without a Base-compatible wallet or USDC balance
- —High-volume batch workloads where $0.02/request adds up quickly
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/116 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>" \
-d '{}'Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base), but the specific functionality of /api/v1/inbox/116 is completely undocumented — it does not appear in the provider's own catalog. No OpenAPI spec, no input/output schema, and no example responses are available.
Warnings
- —The endpoint path /api/v1/inbox/116 is not listed in the provider's public API catalog — its purpose is unknown.
- —No OpenAPI spec or schema documentation is available for this or any endpoint on the site.
- —The /api, /pricing, and /README pages all returned only a 'Connect wallet' prompt with no useful content.
- —Without knowing what this endpoint does, callers risk paying $0.02 for an unknown response.
Citations
- —The provider lists APIs across data & analytics, AI & ML, finance & Web3, and infrastructure — all at $0.02/request.https://lowpaymentfee.com
- —Pricing is $0.02 per request with no API keys, no rate limits, and instant access on Base network.https://lowpaymentfee.com
- —x402 challenge returns maxAmountRequired of 20000 base units in USDC (6 decimals) = $0.02, settled on Base.https://lowpaymentfee.com/api/v1/inbox/116