Topic Terms

What is a VPN Kill Switch?

A VPN kill switch is a safety feature that automatically blocks all internet traffic if your VPN connection drops unexpectedly, preventing your real IP address and unencrypted data from being exposed.

A VPN kill switch is one of the most important safety features a VPN can offer. When your VPN connection drops — whether from a server issue, network hiccup, or switching Wi-Fi networks — there's a window of time before the VPN reconnects during which your device reverts to your normal internet connection. Your real IP address is exposed, and your traffic is unencrypted.

A kill switch closes that window by cutting off all internet access the moment the VPN tunnel fails. It sits between your device and the internet, acting as a failsafe that prevents any data from leaking.

System-Level vs. App-Level Kill Switch

Most VPN clients offer two types:

  • System-level (network) kill switch — Blocks all internet traffic on the device if the VPN drops, regardless of which app is sending it. This is the most comprehensive protection.
  • App-level kill switch — Lets you specify which applications are blocked when the VPN is disconnected. Other apps can still use the internet normally.

App-level kill switches (sometimes called "split-tunneling with kill switch") are useful if you only care about certain apps — a BitTorrent client, for example — staying protected.

Why Kill Switches Matter

Even a two-second VPN drop can expose your IP address to every site and service you're connected to. For someone using a VPN because they:

…that two-second slip is a real problem.

Kill Switch and DNS Leaks

A kill switch prevents your IP from being exposed when the VPN drops entirely, but it doesn't protect against DNS leaks — a separate issue where DNS queries bypass the VPN tunnel even while the VPN is connected. A fully secure setup requires both a kill switch and DNS leak protection.

Which VPNs Have Kill Switches?

Most reputable VPNs include kill switches in their desktop apps. Mobile implementation varies — iOS in particular has platform-level restrictions that make true kill switches harder to implement. NordVPN, ExpressVPN, Mullvad, and Surfshark all offer kill switch functionality in their apps across major platforms.

When evaluating a VPN, always verify that the kill switch is enabled by default, or at minimum, that it's easy to turn on. Some providers bury this option deep in settings.

Related Terms