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 collection 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, 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/17` is listed as "Premium API Access" and was confirmed live via a 402 challenge. Its maxAmountRequired is 20,000 base units of USDC (6 decimals), which equals $0.02. Payment is made to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` on Base, with a 300-second timeout. The endpoint accepts HTTP POST and returns `application/json`.
Documentation beyond the landing page is sparse — the /api, /pricing, and /README routes all resolve to a wallet-connect prompt with no additional content. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawled material. The purpose of the `/api/v1/inbox/17` path specifically (as opposed to the named endpoints like `/api/v2/ai/sentiment`) is unclear; it may be a generic or catch-all premium access route.
Capabilities
Use cases
- —Querying real-time financial data (prices, exchange rates, gas estimates) without API key management
- —Running AI inference tasks (sentiment analysis, summarization, classification, embeddings) on a per-request payment basis
- —Accessing utility services like geocoding, validation, and data conversion with minimal friction
- —Integrating pay-per-use endpoints into autonomous AI agents via x402 protocol
Fit
Best for
- —Developers wanting zero-signup, pay-as-you-go API access
- —AI agents that can settle payments autonomously via x402/USDC on Base
- —Low-volume or bursty workloads where subscription pricing is wasteful
Not for
- —High-volume production workloads needing SLAs, guaranteed uptime, or dedicated support
- —Users who need detailed API documentation, request/response schemas, or SDKs before integrating
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/17 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Example
Request
{
"url": "https://lowpaymentfee.com/api/v1/inbox/17",
"body": {},
"method": "POST",
"headers": {
"X-PAYMENT": "<x402-payment-token>",
"Content-Type": "application/json"
}
}Endpoint
Quality
The endpoint is confirmed live via a valid 402 challenge and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation for the specific /inbox/17 path, and the /api, /pricing, /README pages are all empty wallet-connect prompts. The purpose and expected input/output of this specific endpoint are unknown.
Warnings
- —No OpenAPI or schema documentation available for any endpoint
- —The specific path /api/v1/inbox/17 is not listed among the named endpoints on the landing page — its purpose is unclear
- —All documentation pages (/api, /pricing, /README) resolve to empty wallet-connect prompts with no content
- —No example requests or responses are documented anywhere in the crawled material
Citations
- —All endpoints priced at $0.02 per request with no API keys, no rate limitshttps://lowpaymentfee.com
- —Endpoint categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com
- —402 challenge confirms maxAmountRequired of 20000 base units USDC on Base network with 300s timeouthttps://lowpaymentfee.com/api/v1/inbox/17
- —Payment asset is USDC at contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/inbox/17