Most Popular Extensions

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µBlock

The most efficient blocker for Firefox.

No ads, no tracking, and insanely faster page loads.

Rated 4 out of 5 stars (227)
112,317 users

VKontakte.ru Downloader (music/videos/photos @ VK) Requires Restart

Download music, videos and photos from VK.com / vkontakte.ru. One-click download, natural filenames, displaying file size and bitrate for music, downloading HD video, downloading HQ photos. No spam, no usage of your account, no spyware.

Rated 4 out of 5 stars (496)
111,683 users

Mozilla Archive Format, with MHT and Faithful Save Requires Restart

— Open web pages saved with Internet Explorer or other browsers (MHT)
— Save many tabs, video and audio reliably, in a single ZIP file (MAFF)
— Return to the original site you saved a page from, and more!

Rated 4 out of 5 stars (253)
111,146 users

Screengrab (fix version) Requires Restart

Screengrab! saves webpages as images.
0.99 released!
New features: upload to internet

Rated 5 out of 5 stars (259)
106,134 users

Image Zoom Requires Restart

Adds zoom and rotation functionality for images...

Rated 4 out of 5 stars (341)
104,321 users

Live HTTP Headers Requires Restart

View HTTP headers of a page and while browsing.

Rated 4 out of 5 stars (172)
98,792 users

Theme Font & Size Changer

Theme Font & Size Changer lets you change the global font size and font family used for the user interface in Firefox. Design your browser with your favorite font.

Rated 5 out of 5 stars (174)
97,734 users

JavaScript Debugger Requires Restart

As of Firefox 33, Venkman *no longer works*, as the APIs which it needs have been removed.

Venkman is the code name for Mozilla's JavaScript Debugger. Venkman aimed to provide a powerful JavaScript debugging environment for Mozilla based browsers.

Rated 4 out of 5 stars (50)
92,644 users

Youtube MP3 Podcaster Requires Restart

Self contained add-on for downloading youtube videos to mp3 for easy listening on podcasting gadgets like a Zune or iPod

Rated 4 out of 5 stars (238)
91,990 users

Remote XUL Manager

Manages the Remote XUL whitelist to allow websites and local files to load XUL content. For versions compatible with Firefox 41 and lower, see All Versions page below.

Rated 5 out of 5 stars (37)
89,063 users

gContactSync Requires Restart

Synchronizes contacts & groups between Thunderbird or SeaMonkey and Google Contacts. Imports Facebook friends, contacts you follow on Twitter, and more.

Rated 4 out of 5 stars (224)
87,788 users

UnMHT

UnMHT allows you to view MHT (MHTML) web archive format files, and save complete web pages, including text and graphics, into a single MHT file in Firefox/SeaMonkey.

Rated 4 out of 5 stars (240)
86,982 users

ChatZilla Requires Restart

A clean, easy to use and highly extensible Internet Relay Chat (IRC) client.

Rated 4 out of 5 stars (128)
81,066 users

DOM Inspector Requires Restart

DOM Inspector is a tool that can be used to inspect and edit the live DOM of any web document or XUL application. The DOM can be navigated using a two-paned window displaying a variety of different views on the document and all nodes within.

Rated 5 out of 5 stars (72)
79,607 users

Saved Password Editor Requires Restart

Adds the ability to create and edit entries in the password manager.

Rated 5 out of 5 stars (260)
78,396 users

adaware ad block

By blocking annoying ads and nosy trackers, adaware ad block nearly doubles your browsing speed! And with the most robust antivirus-level cloud-scanning technology of any ad blocker on the market, you’ll be safe from the latest cyber-threats.

Rated 4 out of 5 stars (56)
76,577 users

Copy Urls Expert Requires Restart

Copy multiple urls (links) to clipboard. Provides options to copy urls of all opened tabs and urls in selected text. You can customize the format of copied urls. You can also open multiple links from clipboard.

Rated 5 out of 5 stars (77)
75,653 users

Thumbnail Zoom Plus Requires Restart

Shows full image when you hover over a thumbnail. Works with Amazon, Baidu Images, Bing Images, Facebook, Flickr, Google+, Google Images, IMDb, LinkedIn, Netflix, Pinterest, Reddit, Twitter, Yandex, YouTube, Wikipedia, Yahoo Images, & many more.

Rated 4 out of 5 stars (324)
75,487 users

Bluhell Firewall

Get a faster browsing experience by blocking nasty web resources using Bluhell Firewall, the lightweight Ad-Blocker and Tracking/Privacy Protector.

Rated 4 out of 5 stars (417)
72,480 users

Decentraleyes

Protects you against tracking through "free", centralized, content delivery. It prevents a lot of requests from reaching networks like Google Hosted Libraries, and serves local files to keep sites from breaking. Complements regular content blockers.

Rated 5 out of 5 stars (142)
70,827 users