Pay-per-call API platform on Base network via x402 — $0.02/request in USDC.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a broad catalog of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and utility services. Every endpoint costs $0.02 per request, paid in USDC on the Base network with no API keys, no rate limits, and no commitments required. The x402 protocol handles payment inline: callers receive a 402 challenge with payment details, settle in USDC, and get their response.
The specific endpoint at `/api/v1/transactions/153` is listed as "Premium API Access" and returns an x402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. The endpoint accepts POST requests and returns application/json. However, the exact functionality of this particular transactions endpoint is not documented — the site's landing page lists categories like analytics, AI, finance, and utilities, but does not describe a `/transactions/153` route specifically.
The broader platform advertises endpoints for sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and generation — all at the same $0.02 price point. Documentation pages beyond the landing page were effectively empty (showing only "Connect wallet"), so detailed request/response schemas for any endpoint are unavailable.
Capabilities
Use cases
- —Accessing premium API data without traditional API key registration
- —Making one-off paid API calls settled in USDC on Base
- —Agent-driven workflows that need inline crypto-settled API access
Fit
Best for
- —Developers who want keyless, pay-per-use API access
- —AI agents with x402-compatible payment capabilities
- —Users who prefer crypto micropayments over subscription billing
Not for
- —Users who need detailed API documentation and schemas before integrating
- —High-volume consumers who want bulk pricing or subscription discounts
- —Developers without a Base-network USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transactions/153 \
-H "Content-Type: application/json"
# Returns 402 with x402 payment challenge; attach X-PAYMENT header after settling USDC on Base.Example
Response
{
"error": "X-PAYMENT header is required",
"accepts": [
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"extra": {
"name": "USD Coin",
"version": "2"
},
"payTo": "0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3",
"scheme": "exact",
"network": "base",
"mimeType": "application/json",
"resource": "https://lowpaymentfee.com/api/v1/transactions/153",
"description": "Premium API Access",
"maxAmountRequired": "20000",
"maxTimeoutSeconds": 300
}
],
"x402Version": 1
}Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing ($0.02 USDC on Base). However, the specific functionality of /api/v1/transactions/153 is undocumented, no request/response schemas are available, and all documentation pages beyond the landing page are empty. The listing is largely inferred from the landing page and the 402 challenge.
Warnings
- —The exact purpose and response format of /api/v1/transactions/153 is not documented anywhere in the crawled material.
- —All documentation pages (/docs, /api, /pricing, /README) returned only 'Connect wallet' with no actual content.
- —No OpenAPI spec, request schema, or response schema is available for any endpoint on this platform.
- —The broad catalog of endpoints (AI, analytics, finance, utilities) is advertised but none have verifiable documentation.
Citations
- —The endpoint returns a 402 challenge requesting 20,000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/transactions/153
- —All endpoints cost $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/transactions/153