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 collection of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and general utility services. All endpoints are paid per-request using USDC on the Base network via the x402 protocol — no API keys, no rate limits, and no subscriptions required.
The specific endpoint at `/api/v1/invoices/36` is listed as "Premium API Access" and costs up to $0.02 per call (maxAmountRequired of 20,000 base units of USDC with 6 decimals). The broader platform advertises a uniform $0.02/request price across all its endpoints. Categories of available APIs include: 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).
Documentation 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 schema, no request/response examples, and no detailed descriptions of what each endpoint actually returns. The x402 challenge is live and well-formed, confirming the endpoint accepts POST requests and settles payments to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 in USDC on Base.
Capabilities
Use cases
- —Accessing AI inference (sentiment, summarization, classification, embeddings) without API key management
- —Fetching real-time financial data and crypto gas estimates on a per-call basis
- —Running geocoding or data validation tasks with instant USDC micropayments
- —Exporting analytics data or generating reports without subscriptions
Fit
Best for
- —Agents or bots that need keyless, pay-per-use API access
- —Developers who want to avoid subscription commitments for occasional API calls
- —Web3-native applications that can settle payments in USDC on Base
Not for
- —High-volume production workloads where per-request pricing at $0.02 adds up quickly
- —Users who need detailed API documentation, schemas, or SLAs before integrating
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/invoices/36 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The x402 challenge is live and well-formed, confirming the endpoint works and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI schema, no request/response examples, and all documentation pages are empty beyond a wallet-connect prompt. The specific purpose of /api/v1/invoices/36 is unclear beyond the generic label 'Premium API Access'.
Warnings
- —Documentation pages (/docs, /api, /pricing, /README) are effectively empty — only showing 'Connect wallet'
- —No OpenAPI or JSON schema available for any endpoint
- —The specific function of /api/v1/invoices/36 is not documented — 'Premium API Access' is vague
- —No request or response examples are available anywhere in the crawled content
- —Cannot verify what data or functionality any of the advertised endpoints actually return
Citations
- —Uniform pricing of $0.02 per request across all endpointshttps://lowpaymentfee.com
- —No API keys, no rate limits, instant access, Base networkhttps://lowpaymentfee.com
- —x402 challenge returns maxAmountRequired of 20000 base units USDC on Basehttps://lowpaymentfee.com/api/v1/invoices/36
- —Payment address is 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3https://lowpaymentfee.com/api/v1/invoices/36
- —USDC asset contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Basehttps://lowpaymentfee.com/api/v1/invoices/36
- —Available API categories include Data & Analytics, AI & ML, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com