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 exposes a broad set 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, settled in USDC on the Base network via the x402 protocol.
The specific endpoint `/api/v1/inbox/93` is listed as "Premium API Access" and returns a valid x402 402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base, 6 decimals = $0.02). Payment is made via the `exact` scheme with a 300-second timeout. No API keys or rate limits are advertised; access is gated purely by per-request micropayment.
Documentation is minimal — the landing page lists available endpoints and pricing, but there is no OpenAPI spec, no request/response schema documentation, and no usage examples. The `/api`, `/pricing`, and `/README` pages all resolve to a "Connect wallet" prompt with no additional content. Because of this, the actual behavior and response format of each endpoint (including `/api/v1/inbox/93`) cannot be confirmed from available materials.
Capabilities
Use cases
- —Agent-driven data retrieval without API key management
- —On-demand AI inference (sentiment, summarization, classification, embeddings) paid per call
- —Fetching real-time crypto prices, gas estimates, or exchange rates via micropayment
- —Geocoding or data validation as a utility service with no subscription commitment
Fit
Best for
- —AI agents needing keyless, pay-per-use API access
- —Developers who want to avoid subscription overhead for occasional API calls
- —Web3-native applications that can settle USDC on Base
Not for
- —High-volume batch processing where per-request costs add up quickly
- —Users who need detailed API documentation or guaranteed SLAs
- —Applications requiring non-crypto payment methods
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/93 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no usage examples, and no documentation beyond a landing page listing endpoints. The purpose of '/api/v1/inbox/93' specifically is unclear — it is not listed among the named endpoints on the homepage. This is effectively a stub listing.
Warnings
- —No OpenAPI or schema documentation available for any endpoint
- —The specific path /api/v1/inbox/93 is not listed among the named endpoints on the landing page — its purpose is unknown
- —No request body schema or response format documented anywhere
- —All sub-pages (/api, /pricing, /README) return only a 'Connect wallet' prompt with no content
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
- —The x402 challenge for /api/v1/inbox/93 requests maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/inbox/93
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com