WebRTC lets browsers talk to each other directly for calls and screen sharing. To set that up, the browser gathers its network addresses, and a page can ask to see them. Those connections do not always go through the proxy.
Antidetect browsers handle this per profile, usually with a setting that makes WebRTC report the proxy's address. In an ordinary browser it can be limited with an extension or a setting. After changing it, open a leak-test page through the proxy and check that only the proxy's address appears.
The leak is a browser matter. Scripts that send plain requests have no WebRTC at all, so it does not affect them. It matters to people who browse through a proxy, and to automated browsers that leave the feature switched on.
Questions about webRTC leak
How do I test for a WebRTC leak?
Open a WebRTC leak test page through the proxy. Your real IP address should not appear anywhere on it.
Should I just turn WebRTC off?
For scraping, yes. For accounts, switching it off can itself stand out, because nearly all real browsers have it on. Making it report the proxy's address is the quieter option.
Related terms
- DNS leak
- A DNS leak is when a program looks up site names through your own network instead of through the proxy, revealing which sites you visit.
- Browser fingerprint
- A browser fingerprint is the mix of details a browser reveals, such as screen size, fonts and graphics card, that together single it out.
- Antidetect browser
- An antidetect browser runs many separate browser profiles, each with its own fingerprint, cookies and proxy, so they look like different people.
Read next: How to test a proxy