Privacy
WebRTC Leak Test
Which addresses WebRTC reveals to a page, whether any of them differ from the public address this server sees, and whether your browser is hiding them behind mDNS.
Preparing checks…
How this works
The page opens a WebRTC peer connection to a public STUN server and records the ICE candidates it returns. Each candidate carries an address and a type. The addresses are then compared against the public IP this server observed for your request.
Input
- No input required
Output
- Whether WebRTC is available
- Public addresses gathered over WebRTC
- Private and link-local addresses
- Whether mDNS is hiding local addresses
- Whether any gathered address differs from your public IP
Privacy
The addresses gathered here are displayed to you and are never sent to this server. The connection is made to a public STUN server, which necessarily learns your public address, as any server you contact does.
Limitations
- A differing address is evidence, not proof of a leak: dual-stack and split-tunnel setups cause it legitimately.
- Private addresses such as 192.168.x.x are visible to any page that asks and do not reveal your public IP.
- If STUN is blocked, the result is unknown — blocked is not the same as leaking.
- This does not test DNS behaviour. A separate DNS leak test would be required for that.
Frequently asked questions
What is a WebRTC leak?
WebRTC needs to know your network addresses to establish peer connections. Historically it could reveal your local and public addresses to a page even when you were using a VPN. Browsers now hide local addresses behind random mDNS hostnames by default.
Why does my result say mDNS?
Your browser replaced your local address with a random hostname ending in .local. That is the protection working, not a problem.
I see a private address such as 192.168.1.5. Is that a leak?
It is an exposure to the page, but it is not your public identity and it is not routable on the internet. It is reported as information, not as a leak.
The test says unknown. What does that mean?
No STUN server could be reached, so no candidates were gathered. Firewalls, corporate networks and browser settings commonly block STUN. This is not evidence of a leak.