There is a lot of useful information about Firefox hidden away behind the about: URL protocol. The most useful is the URL about:config, which displays preferences and settings that can be inspected and changed. Here is a complete list of URLs in the about: pseudo protocol:
about: page |
Description |
|---|---|
about: |
Displays version and build information and links to the contributors, licensing information and build configuration |
about:about |
Provides an overview of all about: pages |
about:accounts |
Page used by the Sync feature |
about:addons |
Add-ons Manager |
about:app-manager |
App Manager |
about:buildconfig |
Displays the configuration and platform used to build Firefox |
about:cache |
Displays information about the memory, disk, and appcache |
about:compartments |
Displayed information about compartments; since Firefox 26, that information can be found in the "Other Measurements" section of about:memory. |
about:config |
Provides a way to inspect and change Firefox preferences and settings |
about:crashes |
Lists all crashes, which happened during the runtime of Firefox (in case the user enabled the crash reporter) |
about:credits |
Lists all contributors to the Firefox project |
about:customizing |
Switches to the customization page, which allows to customize Firefox' UI |
about:downloads |
Displays all downloads done within Firefox |
about:healthreport |
Displays performance information of Firefox (in case the user enabled the health report) |
about:home |
Start page of Firefox when opening a new window |
about:license |
Displays licensing information |
about:logo |
Firefox logo |
about:memory |
Provides a way to display memory usage, save it as report and run the GC and CC |
about:mozilla |
Special page showing a message from "The Book of Mozilla" |
about:networking |
Displays networking information |
about:newtab |
Start page when opening a new tab |
about:permissions |
Provides a way to display and manage website permissions. Removed in Firefox 45 (bug 933917) |
about:plugins |
Displays information about installed plugins |
about:preferences |
Firefox settings (also available through Firefox menu > Options) |
about:privatebrowsing |
Start page when opening a private window |
about:reader |
Indicates a web page has Firefox Reader View turned on. See Firefox Reader View for clutter-free web pages |
about:rights |
Displays rights information |
about:robots |
Special page showing notes about robots |
about:sessionrestore |
Session restoration (displayed after a Firefox crash) |
about:support |
Troubleshooting information (also available through Firefox menu > ? (question mark) > Troubleshooting Information) |
about:sync-log |
Displays a synchronization protocol related to the Sync feature |
about:sync-progress |
Page displayed after the Sync feature got set up |
about:sync-tabs |
Lists tabs available for synchronization related to the Sync feature |
about:telemetry |
Displays telemetry data collected and sent to Mozilla while Firefox is running (in case the user enabled telemetry) |
about:webrtc |
Information about WebRTC usage |
about:welcomeback |
Information page displayed after Firefox is reset |
These URLs are defined in docshell/base/nsAboutRedirector.cpp within the kRedirMap array. The array maps most of the URLs, like config to URLs in the chrome: pseudo protocol, such as chrome://global/content/config.xul. The about location information is duplicated in docshell/build/nsDocShellModule.cpp.
Note: You must access about: protocol pages by typing them into the address bar. Attempts to navigate through window.location will throw — Error: Access to 'about:addons' from script denied.