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WebRTC leak test

Check whether WebRTC in your browser reveals a public IP that differs from your VPN address. Runs locally with standard browser APIs and explains each result.

Last updated: 1 min read By: Panthera Project Editorial Team

On this page
  1. What WebRTC can reveal
  2. How to read the result
  3. About “masked” local addresses
  4. Fixing a WebRTC leak
  5. Privacy note

What WebRTC can reveal

WebRTC lets browsers make direct audio, video and data connections. To find a path between peers it gathers ICE candidates: your local network addresses (host candidates) and the public address a STUN server sees (server-reflexive or srflx candidates).

If your VPN routes web traffic but lets this STUN request go out another way, a website could learn your real public IP even with the VPN on.

How to read the result

  • Match: the WebRTC public address equals the address our web server saw. With a VPN on, both are the VPN’s address. ✅
  • Mismatch: WebRTC exposed a different public address. If one of them is your ISP address, that’s a leak.
  • No public address: STUN was blocked by the browser, an extension or a VPN that blocks UDP. Not a leak, but inconclusive.

About “masked” local addresses

Modern Chrome, Edge, Firefox and Safari replace local IP addresses with random .local mDNS names unless a page has camera or microphone permission. If you see something.local (masked), your local address is hidden as intended.

Fixing a WebRTC leak

  • Use a VPN app with a system-level tunnel and kill switch, not a browser-only proxy extension.
  • Firefox: set media.peerconnection.enabled to false in about:config if you never use web calls.
  • Chromium-based browsers: use the VPN’s own extension settings or a WebRTC policy extension to restrict non-proxied UDP.

Privacy note

The test contacts one public STUN server (stun.cloudflare.com) so your browser can learn its public address. Results stay in your browser. Only our standard /api/ip lookup is sent to our server for comparison.

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