Pay-per-call API platform on Base (USDC) offering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-enabled API platform that provides a broad suite of endpoints across four 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 priced at $0.02 per request, payable in USDC on the Base network via the x402 protocol.
The specific endpoint `/api/v1/inbox/32` is listed as "Premium API Access" and carries a maxAmountRequired of 20,000 base units of USDC (0x8335…2913 on Base, 6 decimals), which equals $0.02 — consistent with the site-wide pricing. Payment is made per-call via the x402 exact scheme with no API keys, no rate limits, and no upfront commitments required. The x402 challenge was confirmed live, returning a proper 402 with version 1 challenge.
Documentation is minimal: the landing page lists available endpoints and pricing, but the /api, /pricing, and /README pages all resolve to a bare "Connect wallet" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema documentation, and no usage examples. The purpose of the `/api/v1/inbox/32` path specifically (as opposed to the named category endpoints) is unclear — it may be a generic or catch-all premium endpoint, but this is not documented.
Capabilities
Use cases
- —Agents needing on-demand AI inference (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time crypto gas estimates or token price quotes with per-call payment
- —Geocoding or data validation as a utility service paid per request via x402
- —Exporting analytics data or generating reports on a pay-as-you-go basis
Fit
Best for
- —AI agents that need low-friction, keyless API access on Base
- —Developers wanting simple per-call pricing without subscriptions
- —Web3-native applications that can settle payments in USDC on Base
Not for
- —High-volume batch processing where $0.02/call adds up quickly
- —Users who need detailed API documentation, SDKs, or OpenAPI specs before integrating
- —Applications requiring non-crypto payment methods
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/32 \
-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/request in USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond a landing page listing, and the specific purpose of /api/v1/inbox/32 is undocumented. The /api, /pricing, and /README pages are all empty wallet-connect prompts.
Warnings
- —No OpenAPI spec or request/response schema available
- —The specific endpoint /api/v1/inbox/32 ('Premium API Access') has no documentation explaining what it does or what input it expects
- —All documentation pages (/api, /pricing, /README) resolve to a bare 'Connect wallet' page with no content
- —The breadth of advertised capabilities (AI, finance, geocoding, etc.) cannot be verified from available documentation
Citations
- —All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com
- —x402 challenge returns maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base networkhttps://lowpaymentfee.com/api/v1/inbox/32