WebRTC Leak Test
WebRTC helps browsers make peer connections. Along the way it asks STUN servers for addresses, which can include your local LAN IP or your real public IP even when HTTPS uses a VPN.
What a WebRTC leak looks like
The InstantIPCheck WebRTC leak test opens STUN sessions and lists the candidates. If you see a private 192.168/10.x address, that is a local leak. If you see your ISP’s public IP while the homepage IP is a VPN, the VPN is not covering WebRTC.
How to reduce WebRTC leaks
Use a browser with WebRTC disabled or restricted (some privacy browsers block the constructor). In Firefox, set media.peerconnection.enabled to false if you do not need calls. Chromium users often rely on the VPN’s leak-protection toggle. Re-run this WebRTC leak test after changing settings.