Pay-per-request API platform on Base via x402 — $0.02/call for data, AI, finance, and utility endpoints.
What it does
lowpaymentfee.com is a pay-per-request API platform that uses the x402 protocol to accept USDC payments on the Base network. The specific endpoint `/api/v1/inbox/103` is listed as "Premium API Access" and costs $0.02 per request (20,000 base units of USDC with 6 decimals). No API keys, rate limits, or upfront commitments are required — each call is paid individually via an X-PAYMENT header.
The broader platform advertises multiple API 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 utilities (geocoding, validation, conversion, generation). All endpoints are listed at the same $0.02 per request price point and settle in USDC on Base.
Note that the specific functionality of the `/api/v1/inbox/103` endpoint is unclear — the description is simply "Premium API Access" with no further documentation about what it returns or what input it expects. The docs, pricing, and README pages on the site all render only a "Connect wallet" prompt with no additional technical content. Without an OpenAPI schema or request/response examples, the actual behavior of this endpoint is unknown.
Capabilities
Use cases
- —Accessing a pay-per-request API without needing API keys or subscriptions
- —Making USDC-settled API calls on the Base network via x402
- —Programmatic access to an inbox or messaging endpoint (inferred from URL path)
Fit
Best for
- —Developers who want zero-commitment, pay-as-you-go API access
- —Agents that can settle x402 payments in USDC on Base
- —Use cases requiring no rate limits and instant access
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —Anyone without a Base-compatible USDC wallet
- —High-volume use cases where $0.02/request adds up significantly
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/103 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live (returns 402 with a valid x402 challenge), and pricing is clear at $0.02/request in USDC on Base. However, there is no documentation, no OpenAPI schema, no request/response examples, and the actual functionality of /api/v1/inbox/103 is completely undocumented. The docs pages are empty beyond a wallet-connect prompt.
Warnings
- —The specific functionality of /api/v1/inbox/103 is undocumented — 'Premium API Access' is the only description available.
- —No OpenAPI schema, request format, or response format documentation exists.
- —All documentation pages (docs, pricing, README, api) render only 'Connect wallet' with no technical content.
- —The input/output behavior of this endpoint is unknown; integration requires trial and error.
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 in USDC on Basehttps://lowpaymentfee.com/api/v1/inbox/103
- —All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/inbox/103
- —The platform offers Data & Analytics, AI & ML, Finance & Web3, and Infrastructure API categorieshttps://lowpaymentfee.com