Everyone knows about uBlock Origin. Here are Firefox extensions that are nearly as useful but far less discussed.
1. Firefox Multi-Account Containers (Mozilla)
Multi-Account Containers is an official Mozilla extension that lets you isolate sites in separate "containers" — each with its own cookies, cache, and session state.
Practical use: run two Gmail accounts simultaneously. Isolate your banking session from your general browsing. Keep work and personal accounts separate without managing two browser windows.
This is arguably more useful than most ad blockers for people who manage multiple accounts.
2. Bitwarden
Bitwarden is the open source password manager. Free tier is fully functional, self-hosting is an option, and it works across every browser.
The comparison with Firefox's built-in password manager: Bitwarden works across browsers and devices, has better organization (folders, collections), and can be self-hosted. Firefox passwords sync only within Firefox.
3. Temporary Containers
Temporary Containers creates a new disposable container for every tab you open. When the tab closes, all cookies and data from that tab are deleted.
This is the maximally-paranoid browsing mode: no persistent cookies for anything you don't explicitly whitelist. Dramatically reduces long-term tracking.
Works alongside Multi-Account Containers: whitelist sites you want persistent sessions for, and everything else gets isolated.
4. Tree Style Tab
Tree Style Tab moves your tabs to a vertical sidebar on the left and shows them in a hierarchical tree — child tabs (opened from links) are nested under their parent tab.
For heavy tab users: vertical tabs collapse and show more tabs at once than the horizontal tab bar. The hierarchy makes it easy to see how tabs relate to each other.
Requires hiding the standard horizontal tab bar via userChrome.css for the cleanest setup.
5. Weather & Clock Dashboard
Weather & Clock Dashboard replaces the new tab with live weather, a 3-day forecast, world clocks, and a search bar.
If you open new tabs frequently (which everyone does), ambient weather + clock information is genuinely useful. Not a "one more thing to check" — it's there when you open a tab anyway.
MIT open source, no account required, minimal permissions (no <all_urls>).
6. Tabliss
Tabliss is a highly customizable new tab replacement. Photo backgrounds, widgets for time, weather, notes, todos. More customizable than most new tab extensions.
If you want full control over what your new tab shows, Tabliss is the one to try.
7. Firefox Relay
Firefox Relay generates random email aliases that forward to your real address. Sign up for sites with random-abc123@mozmail.com instead of your real email.
When you stop wanting email from a site: delete the alias. One click. The company can't reach you again.
The free tier gives you 5 aliases. Paid plan gives unlimited.
8. Dark Reader
Dark Reader applies a dark theme to any website. Essential for night browsing on sites that don't have native dark modes.
Better than OS-level night mode because it adapts the color inversion to be readable — not just inverting colors.
9. Unpaywall
Unpaywall finds legal free versions of academic papers. When you hit a paywall on a journal article, Unpaywall checks whether an open-access version exists (author manuscript, institutional repository, etc.) and links you to it.
Essential for researchers, students, and curious people who don't have institutional access.
10. Refined GitHub
Refined GitHub adds dozens of small improvements to the GitHub UI — better PR diffing, cleaner code review, improved notifications. If you spend significant time on GitHub, this is worthwhile.
The full feature list is on the extension's GitHub page. Most individual features are subtle, but the cumulative effect of 50+ small improvements is significant.
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