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/7` is listed as "Premium API Access" and returns a live 402 challenge requesting up to 20,000 base units of USDC (0.02 USD, since USDC uses 6 decimals) on Base. Payment is made via the x402 exact scheme to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3, with a 300-second timeout. The endpoint accepts HTTP POST and returns application/json.
Note that while the landing page advertises many endpoints, the crawled documentation pages (/api, /pricing, /README) all returned only a "Connect wallet" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the site. The exact functionality behind `/api/v1/inbox/7` ("Premium API Access") is unclear — it does not map to any of the named endpoints on the landing page. Treat this listing with caution until more documentation surfaces.
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time financial data such as token quotes, gas estimates, and exchange rates
- —Running utility operations like geocoding, validation, and data conversion on a per-call basis
- —Integrating pay-per-use analytics and data export into agent workflows
Fit
Best for
- —AI agents needing low-friction, keyless API access via crypto micropayments
- —Developers prototyping with multiple API categories without subscription commitments
- —Web3-native applications that can settle USDC on Base
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume production workloads that benefit from bulk pricing or rate-limit guarantees
- —Teams that cannot transact in USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/7 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base), but there is no OpenAPI spec, no request/response schema, no usage examples, and the specific endpoint '/api/v1/inbox/7' is not described anywhere on the site. Documentation pages returned only wallet-connect prompts. Functionality must be guessed.
Warnings
- —No OpenAPI or schema documentation available — all doc pages return only 'Connect wallet'
- —The endpoint path /api/v1/inbox/7 does not correspond to any named endpoint on the landing page; its actual functionality is unknown
- —No request body schema or response schema documented anywhere
- —No examples of successful responses available
Citations
- —All endpoints priced at $0.02 per request with no API keys, no rate limits, instant access on Base networkhttps://lowpaymentfee.com
- —Endpoint returns 402 with maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/inbox/7
- —Categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com