Top Picks at a Glance
| Provider | Kill Switch Type | Mobile Kill Switch | Always-On VPN | Price/Mo |
|---|---|---|---|---|
| 1. Mullvad | OS-level (lockdown mode) | Yes (iOS + Android) | Yes | $5.00 |
| 2. NordVPN | App-level + OS-level | Yes | Yes | $3.99 |
| 3. ExpressVPN | Network Lock (OS-level) | Yes | Yes | $8.32 |
| 4. ProtonVPN | OS-level | Yes | Yes | $4.99 |
| 5. PIA | App-level + MACE | Yes (Android) | Yes | $2.03 |
Our Picks in Detail
- Lockdown Mode uses OS-level firewall rules — blocks traffic even if the Mullvad app itself crashes
- Available on Windows, macOS, Linux, iOS, and Android
- No exceptions: when lockdown is on, no traffic escapes without the VPN tunnel
- DAITA obfuscation works alongside kill switch — no feature conflicts
- Open-source: kill switch implementation is publicly auditable
- Lockdown Mode can make it hard to reach LAN devices (router admin, local printers) — needs manual exclusions
- No annual discount — flat $5/month
- Two kill switch modes: app-level (blocks only selected apps) and system-level (blocks all traffic)
- Meshnet lets LAN devices stay accessible while internet kill switch is active
- Kill switch works on Windows, macOS, iOS, Android, and Linux CLI
- App-level mode useful for torrenting (block torrent client if VPN drops, keep browser working)
- Widely tested and independently verified
- iOS kill switch limited by Apple's network extension framework — works but less granular
- System-level kill switch occasionally requires re-enabling after app updates
- Network Lock activates when the app opens — protects even before the tunnel is established
- OS-level implementation on Windows and macOS
- Works on iOS and Android with native network extension
- No traffic leaks detected in independent testing
- Automatically re-enables after reconnect without user action
- Network Lock cannot be configured app-by-app (system-wide only)
- Highest price at $8.32/mo
- Kill switch code is open-source and independently audited
- OS-level implementation on Windows and macOS
- Always-on VPN mode available for automatic reconnect with kill switch
- NetShield works alongside kill switch
- Free tier includes kill switch on paid plans
- Kill switch on iOS uses the platform's built-in Always-On VPN — less configurable than desktop
- Some users report needing to re-enable kill switch after iOS updates
- Kill switch with configurable exclusions — exclude LAN, specific apps, or IPs
- Open-source apps make kill switch implementation verifiable
- MACE blocks malware-hosting domains even if kill switch briefly pauses
- Available on Windows, macOS, Linux, Android; iOS uses Always-On VPN
- 10 simultaneous connections with kill switch on all
- iOS kill switch less robust than Android (platform limitation)
- US jurisdiction — a consideration for privacy-maximizing users
Types of VPN Kill Switches: App-Level vs System-Level
Not all kill switches protect equally:
| Kill Switch Type | How It Works | Traffic Blocked | Best For |
|---|---|---|---|
| System-level (OS firewall) | Adds firewall rules blocking all non-VPN traffic at the OS level | All traffic — every app | Maximum protection; torrenting; journalists |
| App-level | Kills specified apps (e.g., torrent client) if VPN drops | Only selected apps | Users who want internet access to continue for some apps |
| Network Lock (ExpressVPN) | OS-level, active from app launch even before tunnel connects | All traffic from app open | Protection during the connection establishment phase |
| Lockdown Mode (Mullvad) | OS-level, survives app crashes | All traffic — even if app crashes | Highest-assurance protection scenarios |
| Always-On VPN (iOS/Android) | iOS/Android built-in feature — reconnects VPN automatically | Traffic blocked during reconnect | Mobile users who need kill switch without root access |
Kill Switch Gaps: What Can Still Leak
Even with a kill switch enabled, some traffic patterns can escape VPN protection:
- IPv6 leaks: Many VPNs only tunnel IPv4 traffic. If your router and ISP support IPv6, some traffic may use IPv6 instead — bypassing the VPN tunnel. Fix: disable IPv6 in your router settings, or verify your VPN blocks IPv6 (Mullvad, NordVPN, and ExpressVPN all handle this).
- DNS leaks: If your device sends DNS queries outside the VPN tunnel, your ISP can see which domains you're looking up — even if all other traffic is protected. Verify at dnsleaktest.com with your VPN active.
- WebRTC leaks: Browsers use WebRTC for peer connections and may reveal your real IP. The kill switch doesn't block WebRTC — fix this in browser settings or with a VPN browser extension.
- LAN access gap: Most system-level kill switches block access to local network devices (router, NAS, printer) because local traffic routes through the same blocked interface. Mullvad, NordVPN, and PIA all offer LAN exclusion options to allow local network while blocking internet.
How to Test Your VPN Kill Switch
- Connect to your VPN and visit whatismyip.com — confirm it shows your VPN server's IP, not your real IP.
- Enable the kill switch in your VPN settings.
- Simulate a VPN disconnect: right-click your VPN's tray icon and select "disconnect" (don't quit the app).
- Immediately try to open a website in your browser or run
curl ifconfig.mein a terminal. - If the kill switch works: the browser shows a connection error or timeout — no website loads, and curl returns an error.
- If the kill switch fails: you see your real IP address at whatismyip.com or the page loads.
- Reconnect the VPN and verify the IP returns to the VPN server's IP.
Run this test periodically — VPN app updates occasionally change kill switch behaviour, and platform updates (particularly on iOS and macOS) can interfere with network extension behaviour.
Frequently Asked Questions
What is a VPN kill switch?
A VPN kill switch is a security feature that blocks all internet traffic if your VPN connection drops unexpectedly. Without a kill switch, a VPN disconnection exposes your real IP address and sends unencrypted traffic through your normal ISP connection until the VPN reconnects. The kill switch prevents this window of exposure by cutting internet access entirely until the VPN tunnel is restored.
Does every VPN have a kill switch?
No. Many budget and free VPNs lack a reliable kill switch. Among paid services, kill switch quality varies significantly — some offer only app-level kill switches (blocking specific apps), while others implement system-level blocks that prevent all traffic from escaping. The VPNs in this list all have tested, functional kill switches. Verify the feature is enabled in your VPN settings — it's often off by default.
Do VPN kill switches work on iPhone?
iOS imposes restrictions on what network extensions can do, making full kill switch implementation harder than on desktop. The most reliable approach on iPhone is the built-in 'Always-On VPN' setting (Settings → General → VPN & Device Management → VPN), which iOS manages natively and blocks internet during VPN reconnection. Mullvad and ProtonVPN both leverage this iOS feature effectively. Third-party kill switch implementations on iOS are less reliable than on Android or desktop.