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 catalog 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 — no API keys, no rate limits, and no upfront commitments.
The specific endpoint `/api/v1/inbox/78` is listed as "Premium API Access" and was probed live, returning a valid 402 challenge. Its maxAmountRequired is 20,000 base units of USDC (6 decimals), which equals $0.02 — consistent with the site's advertised flat pricing. Payment is sent to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using the "exact" scheme, with a 300-second timeout.
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. The purpose of the `/api/v1/inbox/78` path specifically (as opposed to the named endpoints like `/api/v2/ai/sentiment`) is unclear — it may be a generic or custom inbox endpoint. Without further documentation, the exact input format and response structure cannot be confirmed.
Capabilities
Use cases
- —Calling AI inference endpoints (sentiment, summarization, classification, embeddings) without managing API keys or subscriptions
- —Fetching real-time financial data like token quotes, exchange rates, and gas estimates on a per-request basis
- —Running utility operations such as geocoding, data validation, and format conversion with instant crypto-settled access
- —Exporting analytics data and generating reports via pay-as-you-go endpoints
Fit
Best for
- —Agents and bots that need keyless, pay-per-call API access settled in USDC on Base
- —Developers prototyping with multiple API categories without upfront commitments
- —Web3-native applications that prefer on-chain micropayments over traditional billing
Not for
- —High-volume production workloads where $0.02/request adds up and bulk pricing is needed
- —Users who require detailed API documentation, SDKs, or guaranteed SLAs before integrating
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/78 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge with clear pricing ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response documentation, no examples, and the specific purpose of /api/v1/inbox/78 is unclear. The crawled pages beyond the landing page are empty. This is effectively a stub listing.
Warnings
- —No OpenAPI or schema documentation available for any endpoint
- —The specific path /api/v1/inbox/78 is not listed among the named endpoints on the landing page — its purpose is unclear
- —All non-root pages (/api, /pricing, /README) returned only a 'Connect wallet' prompt with no useful content
- —No request or response examples are available; input format is unknown
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 endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/inbox/78
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com