How to Detect VPN and Proxy Users by IP Address (JavaScript)

Fraud prevention, geo-restriction enforcement, and abuse detection all share a common need: detecting when a user is hiding behind a VPN or proxy . In this tutorial, you'll build a lightweight VPN/proxy detector in JavaScript using IP geolocation and ASN analysis — no paid threat intelligence feeds required. How VPN Detection Works VPN and proxy detection relies on several signals: ASN (Autonomous System) analysis — VPN providers use specific hosting companies (DigitalOcean, AWS, OVH, etc.) Data center IP detection — Residential users don't connect from data centers Geolocation anomalies — Timezone mismatches, impossible travel speeds Known VPN provider ranges — Major VPN companies own identifiable IP blocks We'll combine these signals into a confidence score. Step 1: Get IP Intelligence First, grab an API key from Frostbyte (200 free credits, no card required). async function getIPIntel ( ip ) { const API_KEY = ' your-api-key ' ; const res = await fetch ( `https://api.frostbyte.tools/