WebRTC leak test

Browsers can reveal your real IP through WebRTC even when a VPN is hiding it from websites. This test checks whether yours does — entirely in your browser, with no data sent anywhere.

Probing WebRTC…

What is a WebRTC leak?

WebRTC is a browser feature for peer-to-peer audio, video, and data — used by Google Meet, Discord, and many web apps. To establish a P2P connection, browsers use STUN servers to discover their own IP addresses, including local and behind-NAT addresses. A website can ask the browser to run this discovery silently and read the resulting IPs via JavaScript, bypassing the VPN entirely.

How the test works

Your browser creates a fake RTCPeerConnection, calls createOffer, and reads the resulting ICE candidates. ICE candidates include every IP the browser can find — including your real one, even when a VPN is tunneling all other traffic. The test runs locally; nothing is sent to our servers.

How to fix a WebRTC leak

Three options: (1) Use a VPN that proactively blocks WebRTC leaks (Doppler's iOS and Android apps disable WebRTC outside the tunnel). (2) Install a browser extension that disables WebRTC (uBlock Origin has an option for this). (3) On Firefox, set media.peerconnection.enabled to false in about:config. Disabling WebRTC will break video calls in the browser; use a native app instead.

FAQ

What is WebRTC?+

WebRTC is a W3C standard built into every modern browser for real-time audio, video, and data peer-to-peer communication. It powers Google Meet, Discord web, Zoom web client, and most browser-based video chat. The same APIs that enable P2P calls also let JavaScript discover your local network addresses.

Why does WebRTC leak my real IP even through a VPN?+

Because the WebRTC stack operates below the application layer and queries the network interface directly via STUN. A VPN tunnels traffic at the IP layer but does not block WebRTC's address-discovery calls. The leaked address travels inside the encrypted tunnel — but the browser then hands it to JavaScript on the page, which can send it anywhere.

Which browsers are affected?+

All of them at default settings: Chrome, Edge, Firefox, Safari, Brave, Opera, Arc. Brave includes a WebRTC IP-leak setting that defaults to disabled. Firefox lets you disable WebRTC entirely via about:config. iOS Safari is partially mitigated since iOS 14 but not fully closed.

Does Doppler VPN block WebRTC leaks?+

Yes. Our iOS and Android clients run a local kill-switch that blocks all UDP traffic outside the tunnel, which stops STUN discovery from reaching external servers. On desktop, we recommend pairing the VPN with uBlock Origin's WebRTC toggle or browser-level disable for full coverage.

Will disabling WebRTC break websites?+

It breaks browser-based video calls (Meet, Zoom web, Discord web) and some collaborative tools. It does not affect normal browsing, streaming, or anything that does not need peer-to-peer connections. Native apps for those services do not rely on WebRTC.

Is this test private?+

Yes. The test runs entirely in your browser using the standard RTCPeerConnection API. No IP, no result, and no metadata leaves your device. We do not even log that you ran the test.

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