Advanced and experimental features
Learn tips beyond the basics and try features before they're released to the public.
Configuration Editor for Firefox
Learn about the Firefox about:config page and how to use the Configuration Editor to view, change, or reset advanced preference settings.
Multi-Account Containers
Add Container tabs to Firefox with the Multi-Account Containers add-on, to separate your work and personal browsing.
About Studies
How to opt out of studies
Firefox Nightly Error Collection
Learn about Firefox Nightly's error collection policy.
Sync custom preferences
Firefox Sync gives you the ability to sync your preferences across all your Firefox Desktop devices. Learn more.
DOM events changes introduced in Firefox 66
Firefox 66 introduced DOM events changes for compatibility with legacy content. Learn more.
Canary domain - use-application-dns.net
Network administrators may configure their networks to modify DNS requests for the following special-purpose domain, called a ''canary domain''.
Control audio or video playback with your keyboard
This page explains the technical documentation on how to control media in Firefox by using the Media Session API.
Compact mode workaround in Firefox
Learn about a workaround that lets you active compact mode if you need to. This feature isn't supported and we still recommend using normal mode.
Windows SSO
Use Windows single sign-on (SSO) to log in to Microsoft, work, and school accounts with credentials from your Windows 10 or 11 operating system.
Firefox advanced customization and configuration options
Two types of advanced Firefox customization options, about:config and userChrome.css modifications, are not recommended. Learn more.
