VPN Kill Switch Test Tool: Verify It Works | Security Advisor Hub

A kill switch is supposed to block internet traffic if your VPN drops — so your device doesn’t quietly fall back to your normal connection. The problem: many people assume it works because it’s “enabled,” but never verify it. This tool helps you run a guided drop test and interpret what you see without panic.

What this tool checks (and what it doesn’t)

This tool checks

Connectivity behavior during a VPN drop (do requests fail or continue?).
Public IP changes when the VPN toggles (does it revert to ISP IP?).
Fail-closed vs fail-open signals in real time.

This tool does not prove

Anonymity: accounts/cookies/fingerprinting still identify you.
No-logs: a kill switch test doesn’t validate provider policies.
All apps are protected: this test observes browser-based requests; other apps can behave differently.

Reality anchor: Passing one test ≠ total security. This confirms one important failure mode: accidental traffic leaks during disconnects.

Kill switch live monitor

Not running

This runs a repeating “heartbeat” check and periodically refreshes your public IP. Then you’ll intentionally disconnect/reconnect your VPN to see whether traffic is blocked.

Public IP (best-effort)

—

Start monitor to detect IP changes during drops.

Network label (best-effort)

—

Used only to interpret results (not stored).

Heartbeat status

—

Repeating checks simulate “can the browser reach the internet?”

Observed risk signal

—

We flag “fail-open” behaviors conservatively.

Guided test steps (do this after starting)

Turn your VPN ON and confirm the monitor shows a stable heartbeat.
Enable your VPN’s kill switch (in the VPN app settings).
Trigger a drop: disconnect the VPN (or switch servers) while the monitor is running.
Watch the log: a working kill switch usually causes heartbeats to fail until VPN reconnects.
Reconnect and confirm heartbeats recover and IP stabilizes again.

Tip: The most meaningful test is on public Wi-Fi or when switching networks (hotel Wi-Fi → mobile hotspot), because that’s where drops happen in real life.

Live log

                      — Start the monitor to begin logging —
                    

Results explained (plain English)

✅ “Fail closed” (what you want)

If your VPN disconnects and the monitor shows repeated failures (timeouts/errors) until the VPN reconnects, that’s a strong sign your kill switch is blocking traffic outside the tunnel.

⚠️ “Fail open” (what to fix)

If your VPN disconnects but the heartbeat keeps succeeding and your public IP reverts to your ISP/home/mobile IP, that suggests traffic is escaping normally while the VPN is down. That defeats the purpose of a kill switch for privacy-sensitive use.

🟨 “Mixed/unclear” (very common)

Many VPNs reconnect quickly, so you may see 1–2 failures or a short gap and then recovery. That can be normal — especially when switching servers. Repeat the test and try a longer disconnect (10–15 seconds) to see if the behavior is consistent.

Reality check: even a perfect kill switch doesn’t stop tracking by accounts, cookies, fingerprinting, or device telemetry.

Common false alarms (and what they usually mean)

Heartbeat failures while VPN is ON → the test endpoint may be rate-limited or your network is unstable (re-test).
IP lookups failing → some networks block public IP APIs (this doesn’t automatically mean leak).
Short blips during server switching → common reconnection behavior; repeat with a longer manual disconnect.
Browser shows “connected” but apps differ → kill switches can be app-specific vs system-wide (see limitations).

What this means for your setup (fixes)

If you saw “fail open”: confirm kill switch is enabled, then look for “system-wide kill switch” vs “app kill switch” in your VPN settings.
If you use split tunneling: your browser may be excluded from the tunnel; disable split tunneling for the test.
If your VPN has “auto-connect”: enable it so drops are shorter and less likely to leak.
Re-test on public Wi-Fi: that’s where drops matter most in real life.

Guides: What is a Kill Switch? (How to test it) • Split tunneling explained • VPN not working? fixes

Recommended next steps

Verify leak paths too: VPN Leak Test (IP, DNS, WebRTC)
Sanity-check routing: Check If Your VPN Is Working
If choosing a provider: Best VPNs (2026)
Understand risk boundaries: What VPNs can’t protect you from

Limitations of this tool (important)

Browser-only visibility: this monitors browser requests. Other apps may behave differently during drops.
Fast reconnects can hide leaks: a VPN that reconnects instantly may not show a long failure window.
Network variability: captive portals, corporate Wi-Fi, and mobile networks can cause unrelated drops.
Public IP checks are best-effort: some networks block IP lookup APIs, limiting interpretation.

FAQ

Does a kill switch make me anonymous? No. It prevents one failure mode (traffic escaping during disconnects). Tracking still happens via accounts/cookies/fingerprints.
Why does my kill switch “pass” sometimes and “fail” other times? Split tunneling, app vs system kill switch settings, and network instability can cause inconsistent behavior.
Should I keep kill switch on all the time? For most people, yes — especially on public Wi-Fi and during travel. The trade-off is occasional connectivity friction.
Is a brief leak during switching servers a big deal? It depends on your risk level. For everyday use it may be minor; for privacy-sensitive tasks you want fail-closed behavior.
What’s the simplest way to improve safety? Enable kill switch + auto-connect, avoid split tunneling for sensitive apps, and re-test after VPN updates.

Trust & disclosure

This tool is provided for educational and diagnostic purposes. Results may vary by provider, configuration, device, browser, and network. Learn more: Methodology • Affiliate disclosure.