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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)
113,707 users

Fast Dial

Visual bookmarks for Firefox.

Rated 3 out of 5 stars (2,517)
112,658 users

YouTube ALL HTML5 No Restart Featured

Play all videos on youtube without flash in your preferred size using only HTML5.

Rated 4 out of 5 stars (152)
112,445 users

Toolbar Buttons No Restart Featured

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)
112,168 users

The Addon Bar (Restored) No Restart

Gives you a place to put all your add-on buttons without over-crowding the navigation bar.

Rated 5 out of 5 stars (333)
109,599 users

Thumbnail Zoom Plus Featured

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 (358)
109,417 users

Tree Style Tab

Show tabs like a tree.

Rated 4 out of 5 stars (1,351)
108,816 users

Webmail Ad Blocker No Restart Featured

Expand your email area by blocking and removing ads on the right hand side of the screen when using Gmail, Hotmail, Outlook.com and Yahoo Mail.

Rated 4 out of 5 stars (195)
108,514 users

FEBE

FEBE (Firefox Environment Backup Extension) allows you to quickly and easily backup your Firefox extensions. In fact, it goes beyond just backing up -- It will actually rebuild your extensions individually into installable .xpi files.

Rated 4 out of 5 stars (655)
108,174 users

Tamper Data Featured

Use tamperdata to view and modify HTTP/HTTPS headers and post parameters...

Rated 4 out of 5 stars (137)
107,417 users

TinEye Reverse Image Search

TinEye is a reverse image search engine. The plugin adds a context menu item that allows you to search for an image to find out where it came from, how it is being used, if modified versions of the image exist, or to find higher resolution versions.

Rated 4 out of 5 stars (186)
106,850 users

Simple YouTube to MP3/MP4 Converter and Downloader No Restart

Download youtube videos as mp3/mp4/ogg/webm fast and easy! Adding mirrors everyday to decrease any downtime! We monitor comments and work to fix any problems as soon as possible!

Rated 5 out of 5 stars (35)
105,885 users

Cookies Manager+

Cookies manager to view, edit and create new cookies. It also shows extra information about cookies, allows edit multiple cookies at once and backup/restore them.

Rated 4 out of 5 stars (81)
103,979 users

Tab Groups No Restart Featured

Tab Groups are an easy way to organize a lot of tabs. You can visually group related tabs, switch between groups, and quickly search through all of your tabs to switch to a specific one.

Rated 5 out of 5 stars (455)
101,905 users

Modify Headers

Add, modify and filter the HTTP request headers sent to web servers. This addon is particularly useful for Mobile web development, HTTP testing and privacy.

Rated 4 out of 5 stars (74)
101,480 users

Strict Pop-up Blocker No Restart

Quickly toggle between blocking all pop-up windows and allowing some pop-ups

Rated 4 out of 5 stars (83)
100,727 users

Theme Font & Size Changer No Restart Featured

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 (175)
99,238 users

WhatsApp™ Desktop No Restart

WhatsApp™ Desktop provides an easy access to WhatsApp Web, and notifies you of incoming posts.

Rated 4 out of 5 stars (53)
99,134 users

Fasterfox

The One; The Original Fasterfox Gives performance & network tweaks for Firefox. Fasterfox makes your browsing so much faster!
Make your Sites Faster than a Fox with Fasterfox for FireFox!

Rated 4 out of 5 stars (91)
99,113 users

CLIQZ- search directly in your browser No Restart

CLIQZ is revolutionising Internet navigation. Simply enter search terms or web addresses into your address bar. Instead of searching through search engine pages, you can click your way to a suitable website straight away.

Rated 4 out of 5 stars (49)
98,926 users