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/152` 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 shows a `maxAmountRequired` of 20000 base units of USDC (contract `0x8335…2913` on Base, 6 decimals), which equals $0.02 — consistent with the site's advertised pricing. The endpoint accepts POST requests and returns `application/json`. Payment is settled on-chain to `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` with a 300-second timeout.
Note that the specific functionality behind `/api/v1/inbox/152` is not documented on the provider's landing page — the "inbox" path does not appear in the listed API catalog. It may be a mailbox-style endpoint or an unlisted resource. Without further documentation or an OpenAPI schema, the exact input/output contract for this particular path is unknown. The provider's site pages beyond the landing page (pricing, README, api) all resolve to a minimal "Connect wallet" prompt with no additional documentation.
Capabilities
Use cases
- —Programmatic access to a pay-per-call API without needing API keys or subscriptions
- —Agent-driven workflows that need on-demand API calls settled in USDC on Base
- —Testing x402 payment flows with a low-cost endpoint
Fit
Best for
- —Developers experimenting with x402 payment protocol integrations
- —AI agents that need keyless, pay-as-you-go API access
- —Low-volume or sporadic API consumers who want no commitments
Not for
- —Users who need well-documented, schema-defined API contracts
- —High-volume consumers who would benefit from bulk pricing or subscriptions
- —Anyone without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/152 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The x402 challenge is live and pricing is clear ($0.02 USDC on Base), but there is no OpenAPI schema, no documentation for the specific /inbox/152 path, no request/response examples, and the provider's docs pages are empty. The endpoint's actual functionality is unknown.
Warnings
- —The path /api/v1/inbox/152 does not appear in the provider's listed API catalog — its purpose is undocumented.
- —No OpenAPI schema, request format, or response examples are available for this endpoint.
- —Provider documentation pages (/pricing, /README, /api) return only a 'Connect wallet' prompt with no content.
- —The exact functionality behind 'Premium API Access' at this path is unclear.
Citations
- —All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base network.https://lowpaymentfee.com
- —The provider offers APIs across data & analytics, AI & ML, finance & Web3, and infrastructure categories.https://lowpaymentfee.com
- —x402 challenge returns maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base network.https://lowpaymentfee.com/api/v1/inbox/152