Firefox has accumulated more useful hidden features than most users realize. Some have been there for years. Here are the ones that make the biggest difference to daily browsing.
about:config — The Advanced Settings Panel
Type about:config in the address bar for Firefox's full settings registry. It looks intimidating, but a few specific entries are genuinely useful:
browser.tabs.loadBookmarksInTabs — set to true to open bookmarks in new tabs by default instead of replacing the current tab.
browser.urlbar.trimURLs — set to false to show the full URL including https:// in the address bar. Useful for security awareness.
ui.key.menuAccessKeyFocuses — set to false to prevent the Alt key from activating the menu bar, which can interfere with keyboard shortcuts in web apps.
Picture-in-Picture
Right-click any playing video → "Picture-in-Picture." A floating video player opens that stays above other windows while you work. Works on YouTube, Netflix, Vimeo, and most video sites.
Useful for: following a tutorial while working in another window, keeping a meeting video visible while taking notes, watching something in the background while doing other work.
Multi-Account Containers
Install the Multi-Account Containers extension (official Mozilla add-on). It lets you run multiple sessions of the same site simultaneously — work Google account in a blue container, personal in orange, for example.
Without containers: logging into a second Google account logs you out of the first.
With containers: both sessions run in isolation, permanently.
This is the feature that makes Firefox most useful for people who manage multiple accounts for work.
The about: Page Library
Firefox has over 20 about: pages with useful information:
-
about:memory— detailed memory usage, with a "Minimize Memory Usage" button that can free up hundreds of MB -
about:performance— shows which tabs and extensions are using the most CPU -
about:crashes— list of recent crash reports with links to Mozilla's crash analysis -
about:networking— live network request log -
about:config— the full settings registry (as above)
View Source / Inspector Keyboard Shortcuts
For developers, a quick reference:
-
Ctrl+U— view page source -
F12— open DevTools -
Ctrl+Shift+I— same as F12 -
Ctrl+Shift+K— open the browser console directly (no DevTools required for quick JS evaluation) -
Ctrl+Shift+C— open Inspector in element picker mode (click any element to inspect it)
Reader View Keyboard Shortcut
F9 — toggle Reader View. Works on any article-formatted page. Strips ads, sidebars, and navigation for clean reading. You can set the font, size, and color scheme; preferences persist.
New Tab Customization
The default Firefox new tab shows sponsored shortcuts and top sites. You can:
- Remove sponsored shortcuts: Settings → Home → uncheck "Sponsored shortcuts"
- Replace it entirely: new tab extensions on AMO replace the whole page
Weather & Clock Dashboard replaces the new tab with live weather, a 3-day forecast, world clocks, and a search bar. MIT licensed, no account required.
Screenshot Tool
Ctrl+Shift+S — opens the Firefox screenshot tool. Lets you capture a visible page portion, the full viewport, or the entire page (scrolled). Saves to clipboard or downloads as PNG.
This is faster than using OS screenshot tools for anything you want to clip from the browser.
Tab Management: Ctrl+Tab Recent Ordering
By default, Ctrl+Tab switches tabs in order. You can enable "most recently used" ordering instead: Settings → General → Tabs → check "Ctrl+Tab cycles through tabs in recently used order."
This makes Ctrl+Tab behave like Alt+Tab for windows — switch back to the previous tab with one keystroke.
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