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, 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/127` is listed as "Premium API Access" and returns a valid x402 challenge with a maxAmountRequired of 20,000 base units of USDC (0x8335… on Base), which equals $0.02 given USDC's 6 decimals. Payment is made via the x402 exact scheme to the specified payTo address. The endpoint accepts HTTP POST requests and returns application/json.
Note that while the landing page advertises many endpoints, the crawled documentation is extremely thin — the /api, /pricing, and /README pages all returned only a "Connect wallet" prompt with no further detail. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available. The actual functionality behind this particular inbox endpoint and the broader catalog cannot be verified from the crawl material alone.
Capabilities
Use cases
- —Accessing AI inference (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time crypto prices, gas estimates, and exchange rates on a per-call basis
- —Running geocoding or data validation utilities with instant USDC micropayments
- —Exporting analytics data or generating reports with no subscription commitment
Fit
Best for
- —Agents or bots that need frictionless, key-free API access via crypto micropayments
- —Developers prototyping with multiple utility endpoints at low per-call cost
- —Web3-native applications that already hold USDC on Base
Not for
- —High-volume production workloads where $0.02/request adds up significantly
- —Users who need detailed SLAs, rate-limit guarantees, or enterprise support
- —Developers without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/127 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Example
Request
{
"url": "https://lowpaymentfee.com/api/v1/inbox/127",
"body": {},
"method": "POST",
"headers": {
"X-PAYMENT": "<x402-payment-token>",
"Content-Type": "application/json"
}
}Endpoint
Quality
The x402 challenge is live and well-formed, confirming the endpoint exists and its price ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no usage examples, and the documentation pages are effectively empty. The purpose of this specific 'inbox/127' endpoint is unclear beyond the generic 'Premium API Access' label.
Warnings
- —No OpenAPI or schema documentation available — request and response formats are unknown
- —The /api, /pricing, and /README pages returned no useful content (only 'Connect wallet')
- —The specific purpose of /api/v1/inbox/127 ('Premium API Access') is not documented; it may be a generic or placeholder endpoint
- —Broad claims on the landing page (16+ endpoints across 4 categories) cannot be verified from crawl data
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/127 specifies maxAmountRequired of 20000 base units of USDC (asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Basehttps://lowpaymentfee.com/api/v1/inbox/127
- —Endpoint categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com