The most popular Firefox extensions of 2021 were both adblockers

Ad Blocker on Laptop
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Customizing Mozilla's browser (opens in new tab) with add-ons can give you a whole new experience when browsing the web though only one-third of Firefox (opens in new tab) users have installed an extension or theme.

Among the 100m+ users that did install an extension this year, adblockers (opens in new tab) were the most popular with Adblock Plus taking the top spot followed by uBlock Origin. Across the span of 2021, Adblock Plus had an average of over 6.1m daily users while uBlock Origin averaged just over 5m+ daily users over the course of the year.

While Adblock Plus led the charge at the beginning of the year, uBlock Origin was able to close the gap and if current usage trends among Firefox users continue, it may take the top spot in early 2022 according to a new blog post (opens in new tab) from Mozilla.

One of the reasons users choose Firefox as their preferred browser is to further protect their privacy online. While adblockers can stop ads from following you around the web, other popular extensions this year that protect against invasive tracking include Mozilla's own Facebook Container (opens in new tab) with 1.7m daily active users and Ghostery (opens in new tab) with 1.1m daily active users.

In addition to putting out a list of the most popular extensions each year, the Firefox Recommended Extensions program (opens in new tab) is a curated list of third party extensions that meet Mozilla's highest standards of security, utility and user experience.

For those who often find themselves drowning in a sea of open browser tabs, Tab Stash (opens in new tab) may be the perfect extension as it adds a toolbar button that when clicked, saves all of your open tabs as temporary bookmarks. If you're using Firefox Sync (opens in new tab), the service will automatically show your Tab Stash bookmarks synced to other devices.

Another interesting extension highlighted by Mozilla is Stylebot (opens in new tab). This extension gives you the power to dramatically alter the way any website looks from font sizes to color schemes to content layout. Perhaps you're intrigued by vertical tabs (opens in new tab) in Microsoft Edge (opens in new tab)? Then the Sideberry (opens in new tab) extension can be used to organize your open tabs in a cascading “tree” tucked away to the side of your browser.

While web browsers have certainly come a long way, extensions allow you to further customize their look and fell as well as their functionality which can help you be more productive or just have a better browsing experience overall.

We've also rounded up the best browser (opens in new tab), best VPN (opens in new tab) and best proxy (opens in new tab) services

After working with the TechRadar Pro team for the last several years, Anthony is now the security and networking editor at Tom’s Guide where he covers everything from data breaches and ransomware gangs to the best way to cover your whole home or business with Wi-Fi. When not writing, you can find him tinkering with PCs and game consoles, managing cables and upgrading his smart home.