How Sites Detect You're Using a Proxy or VPN

Ever had a banking app or streaming service flag you as “using a VPN” when you weren’t trying to hide anything at all? Proxy and VPN detection is more common - and less mysterious - than it might seem, and it’s worth understanding what’s actually being checked before assuming it’s you specifically that triggered it.

It’s mostly about where the IP came from, not what you’re doing

The core signal isn’t your behavior - it’s the IP address you’re connecting from. Detection services maintain large, continuously updated databases mapping IP ranges to their known origin: residential ISP, mobile carrier, datacenter, or a known commercial VPN/proxy provider. Datacenter and hosting-provider ranges are particularly easy to flag, since ordinary home internet connections essentially never originate from that infrastructure - only servers do, which is a strong signal something automated or proxied is happening. We’ve written separately about why banking and UPI apps specifically tend to block VPN connections, which comes down to exactly this kind of IP-origin check combined with fraud-prevention rules.

Why this isn’t perfectly reliable in either direction

These databases lag reality in both directions. A brand-new VPN exit node or a residential proxy service (which routes traffic through real home connections rather than a datacenter) can go undetected for a while simply because it hasn’t been catalogued yet. Conversely, an IP can get mistakenly flagged if it was previously used by a VPN provider and has since been reassigned to an ordinary residential customer. Detection is a probabilistic signal, not a certainty.

Checking any IP yourself

Our Proxy/VPN Detection Checker runs any IP address against known proxy, VPN, and hosting-provider ranges using a free, keyless detection tier, and reports what it finds. Leave the field blank to check your own current IP - useful for understanding exactly what a site would see if it ran the same check on you. If you’re not sure what your current public IP even is first, our guide to finding your public IP address covers that.

Treat a “not flagged” result as a helpful signal rather than a guarantee - as with any database-driven detection, it won’t catch everything, particularly newer or residential-style proxy services.