Most Popular Extensions

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HTTPS Everywhere

Encrypt the web! HTTPS Everywhere is a Firefox extension to protect your communications by enabling HTTPS encryption automatically on sites that are known to support it, even when you type URLs or follow links that omit the https: prefix.

Rated 4 out of 5 stars (78)
189,570 users

Mozilla Archive Format, with MHT and Faithful Save

— 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 (294)
175,836 users

Enigmail Featured

OpenPGP message encryption and authentication for Thunderbird and SeaMonkey.

Rated 4 out of 5 stars (190)
166,444 users

SaveFrom.net helper all-in-1 / youtube downloader No Restart

SaveFrom.net helper will enable you to download files from YouTube.com, FaceBook.com, Vimeo.com, Daylimotion.com, VK.com, Odnoklassnoki.ru, Soundcloud.com and more than 40 other just in one click.

Rated 4 out of 5 stars (221)
162,535 users

Live HTTP Headers

View HTTP headers of a page and while browsing.

Rated 4 out of 5 stars (168)
160,903 users

Image Zoom

Adds zoom and rotation functionality for images...

Rated 4 out of 5 stars (338)
153,805 users

Screengrab (fix version)

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

Rated 5 out of 5 stars (286)
147,389 users

ChatZilla

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

Rated 4 out of 5 stars (126)
137,205 users

DOM Inspector

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 (66)
130,998 users

Bluhell Firewall No Restart

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

Rated 5 out of 5 stars (275)
130,849 users

Youtube MP3 Podcaster

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 (227)
125,502 users

Youtube Best Video Downloader 2 - MP3 MP4 M4A AAC No Restart

Now with 1080p Full-HD Support!
Direct YouTube downloads MP3 M4A AAC and HD MP4, FLV, 3GP. With just one mouse click! With the click off an mouse button! Super fast downloads right from the Youtube video page you are viewing.

Rated 3 out of 5 stars (42)
125,076 users

Toolbar Buttons No Restart

Adds toolbar buttons to the customize toolbar window in several programs including Firefox, Thunderbird and SeaMonkey. Some of the buttons make commonly preformed actions quicker, others add new functionality.

Rated 4 out of 5 stars (322)
124,519 users

Lucifox

Read EPUB e-books and browse OPDS catalogs.

Rated 4 out of 5 stars (21)
121,409 users

JavaScript Debugger

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)
119,302 users

Thumbnail Zoom Plus

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 (348)
116,681 users

X-notifier (for Gmail,Hotmail,Yahoo,AOL ...)

Notifier for gmail, yahoo, hotmail, aol and more webmails.
X-notifier(aka WebMail Notifier) checks your webmail accounts and notifies the number of unread emails...
Supports : gmail, yahoo, hotmail, POP3/IMAP, facebook, twitter and more

Rated 4 out of 5 stars (1,676)
101,482 users

Theme Font & Size Changer No Restart

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 (170)
101,111 users

IE Tab + (FF 8+, 7, 6, 5, 4, 3.6, 3.5, SeaMonkey)

IE Tab + is an enhanced version of IE Tab. It supports FF 3.5 or greater, integrates IE Tab with Adblock Plus in the IE Tab engine, and synchronizes cookies between IE and Firefox. You can easily import settings from the original IE Tab into IE Tab +

Rated 3 out of 5 stars (86)
99,682 users

RequestPolicy

Be in control of which cross-site requests are allowed. Improve the privacy of your browsing by not letting other sites know your browsing habits. Secure yourself from Cross-Site Request Forgery (CSRF) and other attacks.

Rated 4 out of 5 stars (229)
97,822 users