Direct Answer
A WebRTC leak is when your browser reveals your real public IP address through its built-in WebRTC feature, even while a proxy or VPN is active. WebRTC learns that public IP from a STUN server to enable real-time audio and video, and a web page can read it with a few lines of JavaScript — even with your proxy active — unless you prevent it.
→ Test your own browser now: the free traffic self-check flags a WebRTC leak and shows what a site actually sees about you.
What Is WebRTC?
WebRTC (Web Real-Time Communication) is a standard built into every major browser — Chrome, Firefox, Edge, Safari and others. It powers in-browser video calls, voice chat and peer-to-peer file transfer without plugins. To connect two browsers directly, WebRTC needs to discover the network addresses each device can be reached on. That discovery step is useful for calls — and it is also the source of the leak.
What Is a WebRTC Leak?
A WebRTC leak happens when a website reads the addresses WebRTC discovers and sees your real public IP instead of the proxy you set. You configured a proxy expecting your traffic to show a single, consistent IP. But WebRTC operates at the browser level and can report an address your proxy never touched — so the page sees a mismatch: a proxy IP for normal requests and your real IP through WebRTC.
The result is an inconsistency you did not intend. For anyone relying on a stable, region-true German mobile IP — for ad verification, market research or testing — that mismatch undermines the very thing you set the proxy up to provide. A WebRTC leak is one of three side channels worth checking; the others are covered in what a DNS leak is and the full check your proxy for leaks routine.
Why WebRTC Leaks Happen
WebRTC uses a process called ICE (Interactive Connectivity Establishment), which gathers "candidates" — the possible addresses your device can use. To do this it queries STUN servers, which reply with the public IP they see. A web page can request these candidates through JavaScript and read that public IP.
Your local (private) network address used to leak the same way, but modern browsers — Chrome, Edge and Safari — now mask it behind a random .local hostname (mDNS) by default, so it no longer identifies you. The address that still matters is your real public IP: WebRTC learns it from a STUN server over UDP, and that request can take a path around your proxy.
Crucially, a browser-level HTTP or SOCKS proxy only routes the browser's normal web requests. WebRTC's candidate discovery can take a separate path, so it may surface the real public IP even when your page traffic goes through the proxy. The leak is not a bug — it is WebRTC working as designed, exposing what a proxy at the wrong layer does not cover.
How to Test for a WebRTC Leak
Testing takes a minute:
- Connect through your proxy as you normally would.
- Open a tool that shows your IP and your WebRTC-discovered address side by side. Our check your proxy for leaks guide walks the WebRTC step end to end.
- Compare the two. If the WebRTC address matches your proxy IP, you are consistent. If it shows a different address — especially your real connection — you have a leak.
Run the test in the exact browser and profile you use for work. WebRTC behaviour differs between browsers and even between profiles, so a clean result in one setup does not guarantee another.
How to Prevent a WebRTC Leak
There are two reliable approaches, depending on how you work:
- Control WebRTC in the browser. In Firefox, set
media.peerconnection.enabledtofalseinabout:config. In Chromium-based browsers, use a reputable extension that limits WebRTC's IP exposure, or a multi-profile browser that manages WebRTC per profile. Disabling WebRTC entirely is the strongest option if you do not need in-browser calls. - Route the whole device, not just the browser. When you connect through OpenVPN at the operating-system level, every component — including WebRTC — uses the same German mobile endpoint. There is no separate path to leak through, so the address WebRTC discovers is the proxy IP. This is the most thorough fix, and it is set up in a few minutes on Windows, Android or iPhone.
After applying either fix, test again. Verification is the only way to be sure the leak is closed.
WebRTC Leaks and Mobile Proxies
A German mobile proxy from GermanProxy.io gives you a real German 4G/5G IP, but a browser-level WebRTC leak can still expose your underlying connection alongside it. The goal is consistency: every signal a site reads should point to the same German mobile endpoint. Routing your device through OpenVPN, or controlling WebRTC in your working browser, closes the gap so your real IP stays out of the picture and your sessions look exactly like what they are — a genuine German mobile user.
If you drive a proxy at the request level instead of through a desktop browser, WebRTC often isn't in play at all — a request-based Python setup or headless browser scraping has no browser making peer connections to leak through. None of this is about hiding wrongdoing; it is basic hygiene for clean, reliable data.
FAQ
Does a VPN or proxy stop WebRTC leaks by itself?
Not always. A browser-level proxy only routes the browser's normal requests, so WebRTC can still surface your real public IP. Device-level routing through OpenVPN covers everything, including WebRTC.
Is disabling WebRTC safe?
Yes, with one trade-off: in-browser calls and peer-to-peer features stop working. If you do not use browser video or voice chat for the task at hand, disabling WebRTC is a clean, simple fix.
Can a website always see my WebRTC IP?
Only if WebRTC is enabled and able to discover an address outside your proxy's path. Modern browsers already hide your local network IP behind a random .local hostname, so the public IP is what matters. Close that path — by disabling WebRTC or routing the whole device — and the leak disappears.
CTA
Want every signal to point to the same German mobile IP? Set up your connection over OpenVPN and run all three leak tests — including WebRTC — before you rely on it.
Get a German mobile proxy: Real 4G/5G IPs from Germany, fair-use 20 GB/day — browse German mobile proxy plans or try a shared 5G German proxy.