Pay-per-request API platform on Base via x402 — analytics, AI, finance, and utility endpoints at $0.02/call.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers 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, paid in USDC on the Base network with no API keys, rate limits, or commitments required.
The specific endpoint at `/api/v1/carts/24` is labeled "Premium API Access" and accepts POST requests. 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 via the x402 exact scheme with a 300-second timeout. The endpoint returns application/json.
Documentation beyond the landing page is extremely sparse — the /docs, /api, /pricing, and /README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available. The actual functionality behind the `/api/v1/carts/24` path is unclear; it does not map to any of the advertised API categories listed on the homepage. Agents should treat this endpoint with caution until more documentation is available.
Capabilities
Use cases
- —Accessing AI inference endpoints (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time financial data like token quotes, gas estimates, and exchange rates on a per-call basis
- —Running utility operations such as geocoding, validation, and data conversion with micropayments
- —Integrating pay-per-use analytics and data export into agent workflows
Fit
Best for
- —Agents needing low-cost, no-auth API access on Base
- —Developers prototyping with pay-as-you-go AI and data endpoints
- —Web3-native applications that prefer crypto-settled API calls
Not for
- —High-volume production workloads requiring SLAs and documented schemas
- —Users who need detailed API documentation or OpenAPI specs before integration
- —Applications requiring non-crypto payment methods
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/carts/24 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Example
Request
{
"url": "https://lowpaymentfee.com/api/v1/carts/24",
"body": {},
"method": "POST",
"headers": {
"X-PAYMENT": "<x402-payment-token>",
"Content-Type": "application/json"
}
}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 documentation beyond a landing page, and the specific /api/v1/carts/24 path doesn't correspond to any advertised API category. The docs, pricing, and README pages are all blank beyond a wallet connect prompt.
Warnings
- —No OpenAPI or schema documentation available for any endpoint
- —The /api/v1/carts/24 path does not match any of the advertised API categories on the homepage — its actual functionality is unknown
- —All documentation pages (/docs, /api, /pricing, /README) render only 'Connect wallet' with no useful content
- —No example request or response bodies are documented anywhere
Citations
- —All endpoints priced at $0.02 per request with no API keys, rate limits, or minimumshttps://lowpaymentfee.com
- —Endpoints span Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —Payment via USDC on Base networkhttps://lowpaymentfee.com
- —x402 challenge returns maxAmountRequired of 20000 base units (USDC, 6 decimals = $0.02) with 300s timeouthttps://lowpaymentfee.com/api/v1/carts/24