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 catalog of pay-per-request endpoints settled in USDC on the Base network. The specific endpoint `/api/v1/inbox/18` is listed as "Premium API Access" and costs up to $0.02 per call (20,000 base units of USDC with 6 decimals). Payment is handled via the x402 protocol — no API keys, no subscriptions, no rate limits. Callers attach an `X-PAYMENT` header with a valid payment proof and receive the response immediately.
The broader platform advertises four endpoint 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 listed endpoints share the same $0.02/request pricing.
The specific functionality behind `/api/v1/inbox/18` is not documented beyond the label "Premium API Access." The endpoint accepts POST requests and returns `application/json`. No request body schema, response schema, or usage examples are provided by the site. The crawled /api, /pricing, and /README pages all returned only a "Connect wallet" prompt with no additional documentation.
Capabilities
Use cases
- —Accessing premium API data without subscription or API key management
- —Agent-driven workflows that need instant, per-call payment settlement
- —Programmatic access to a variety of data, AI, finance, and utility services via a single payment protocol
Fit
Best for
- —Developers or agents wanting zero-signup, pay-as-you-go API access
- —x402-compatible clients on the Base network
- —Low-volume or bursty workloads where per-request pricing is preferable to subscriptions
Not for
- —Users who need detailed API documentation or guaranteed SLAs before integrating
- —High-volume consumers who would benefit from bulk pricing or rate-limited tiers
- —Anyone without USDC on Base or an x402-compatible payment client
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/18 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>" \
-d '{}'Example
Request
{
"url": "https://lowpaymentfee.com/api/v1/inbox/18",
"body": {},
"method": "POST",
"headers": {
"X-PAYMENT": "<x402-payment-proof>",
"Content-Type": "application/json"
}
}Endpoint
Quality
The endpoint is live (402 challenge confirmed) and pricing is clear ($0.02 USDC on Base), but there is no documentation for the specific /inbox/18 endpoint — no request schema, no response schema, no examples. The /api, /pricing, and /README pages are all gated behind a wallet connection and yield no useful content. The actual functionality of this endpoint is unknown.
Warnings
- —No documentation available for /api/v1/inbox/18 — the purpose of 'Premium API Access' is unspecified beyond the label
- —No request or response schema provided; callers cannot know what to send or what to expect
- —All documentation pages (/api, /pricing, /README) returned only 'Connect wallet' with no content
- —The broader site lists many endpoint categories but it is unclear whether /inbox/18 maps to any of them
Citations
- —The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/inbox/18
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/inbox/18
- —The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —Endpoint categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com