In our articles, we often mention the about:config command which can be entered in the address bar. That command opens the built-in configuration editor of the Firefox browser and allows performing extreme fine-tuning of the browser. It contains lots of options which are not accessible from the browser's settings interface. Many Firefox users are not even aware that about:config is not the only about: command available in the browser. Firefox comes with a huge set of useful about commands which I would like to share with you today.
Every about: command must be entered in the address bar like URL of a web page:
Firefox allows to extend the default about: commands set using special extensions, but the default list of about: commands in Firefox without add-ons looks as follows:
- about: The same page as "Help -> About" (except that, on some applications, Help → About is a much smaller popup).
- about:about Lists all these about: URLs (Mozilla Suite/SeaMonkey or Firefox 4 and newer only).
- about:accounts Firefox Sync account.
- about:addons The "new" addons manager, in trunk builds dated 2010-05-11 or later.
- about:app-manager App Manager, a tool to help users build and install web apps on compatible devices (i.e. Firefox OS).
- about:buildconfig Reveals details about your Mozilla build options.
- about:cache Displays cache statistics and disk cache directory location.
- about:cache?device=memory Lists memory cache entries.
- about:cache?device=disk Lists disk cache entries.
- about:cache-entry Shows information about a cache entry. Used in about:cache links. Requires parameters.
- about:config GUI for modifying user preferences.
- about:crashes List of Breakpad crash reports, with links and datestamps.
- about:customizing Only available on Australis builds of Firefox, starts the Customize mode.
- about:credits The list of contributors to the Mozilla projects.
- about:downloads Your recent downloads.
- about:home Firefox Start Page.
- about:healthreport Firefox Health Report. Also accessible via "Help -> Firefox Health Report".
- about:licence and about:license both show the Mozilla Public License and the Netscape Public License for the piece of software.
- about:logo Displays the application logo.
- about:memory shows the memory usage of Firefox.
- about:mozilla shows Book of Mozilla
- about:networking Displays the experimental page about network connections in Firefox.
- about:newtab the default new tab page.
- about:permissions shows and manages the permissions as also shown in Tools → Page Info → Permissions.
- about:plugins Lists all your plugins as well as other useful information.
- about:preferences Open preferences.
- about:privatebrowsing Open a new private window.
- about:rights Displays the page "About Your Rights".
- about:robots Easter egg.
- about:sessionrestore Open the "Restore last browsing session" page.
- about:support Displays information such as Application Basics (version, link to open the profile folder, link to about:plugins and about:buildconfig), Extensions, Modified Preferences and Graphics information. Also accessible via "Help -> Troubleshooting information".
- about:sync-log Displays Sync logs.
- about:sync-progress Displays synchronization progress.
- about:telemetryThis page shows the information about performance, hardware, usage and customizations collected by Telemetry. This information is submitted to Mozilla to help improve Mozilla Firefox.
- about:webrtc Will be implemented in near future.
- about:welcomeback The "Firefox is ready to go" page.
This list can be changed by Mozilla with a new release of Firefox. You can always check out the list of about: commands available in your browser by entering the following in the address bar:
Please note that the following about: URLs that are not listed in the about:about page but exist:
- about:blank A blank page. Useful for setting as your homepage.
- about:blocked Used by Safe Browsing tool to display bad web page.
- about:bloat Displays BloatView output in Beta/Nightly builds. BloatView is a tool that shows information about cumulative memory usage and leaks.
- about:certerror Displays "This Connection is Untrusted" if a web page has invalid certificate.
- about:feeds Feed viewer template.
- about:newaddon Dialog shown when one or more add-ons have been added "without" using the normal Add-on Manager procedures, by dropping it in one of the "special" add-on directories. It asks which ones you want to keep enabled. Typing about:newaddon in the URL bar won't display anything. It may briefly flash an empty error dialog, then you get the empty about:blank page.
- about:neterror Displays error page.
- about:socialerror Will be implemented in near future.
- about:tabcrashed Will be implemented in near future.
That's it. Bookmark this page for the future to access the full list of about: commands in Firefox.