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, paid in USDC on the Base network via the x402 protocol.
The specific endpoint `/api/v1/inbox/2` is listed as "Premium API Access" and its x402 challenge advertises a maxAmountRequired of 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. Payment is made per-request with no API keys, no rate limits, and no minimum commitments required. The platform accepts the x402 "exact" payment scheme with a 300-second timeout window.
Note that while the landing page lists many endpoints across multiple categories, the specific function of `/api/v1/inbox/2` (labeled "Premium API Access") is not clearly documented — it does not appear in the public endpoint catalog on the homepage. There is no OpenAPI schema, no request/response examples, and the docs, pricing, and README pages all resolve to a minimal "Connect wallet" prompt with no additional content. The actual behavior of this particular endpoint remains unclear.
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time financial data such as token quotes, exchange rates, and gas estimates
- —Running utility operations like geocoding, validation, and data conversion on a per-call payment basis
- —Integrating pay-per-use data analytics and reporting into agent workflows
Fit
Best for
- —Agents needing low-friction, keyless API access with per-call crypto payments
- —Developers who want to avoid subscription commitments for occasional API usage
- —Web3-native applications that can settle payments in USDC on Base
Not for
- —High-volume production workloads where $0.02/request adds up significantly
- —Users who need detailed API documentation, schemas, or SLAs before integration
- —Applications that cannot make x402 USDC payments on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/2 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The x402 challenge is live and confirms pricing, but the specific endpoint /api/v1/inbox/2 has no documentation, no request/response schema, and no examples. The landing page lists many endpoints but this one is absent from the catalog. Docs/pricing/README pages are empty beyond a wallet connect prompt.
Warnings
- —The endpoint /api/v1/inbox/2 ('Premium API Access') does not appear in the provider's public endpoint catalog — its actual functionality is unknown.
- —No OpenAPI schema, request format, or response examples are available for any endpoint.
- —Documentation pages (/api, /pricing, /README) return only a 'Connect wallet' prompt with no useful content.
- —The broad catalog of 16+ endpoints listed on the homepage cannot be independently verified as functional.
Citations
- —The x402 challenge returns maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base networkhttps://lowpaymentfee.com/api/v1/inbox/2
- —All listed endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —The endpoint is described as 'Premium API Access' in the x402 challengehttps://lowpaymentfee.com/api/v1/inbox/2