Most Popular Extensions
Selenium IDE Requires Restart
Selenium IDE is an integrated development environment for Selenium tests. It is implemented as a Firefox extension, and allows you to record, edit, and debug tests.
Screengrab (fix version) Requires Restart
Screengrab! saves webpages as images.
New features: upload to internet
MeasureIt Requires Restart
Draw a ruler across any webpage to check the width, height, or alignment of page elements in pixels.
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!
Print Edit Requires Restart Featured
Allows editing of web page content while in Print Preview mode, prior to printing or saving as HTML or PDF. Compacts the layout and removes unwanted content such as adverts, sidebars and blank pages. Any element can be formatted, hidden or deleted.
A free extension of the web tool https://emojikeyboard.org. It helps input emoji in the web browser with an extensive search functionality.
Empty Cache Button Requires Restart
Cache clearing made easy. One click.
Modify Headers Requires Restart
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.
Quickly toggle between blocking all pop-up windows and allowing some pop-ups
Youtube Downloader 4K - Video Downloader Requires Restart
Download from YouTube 4K videos and thousands other video websites.
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
Theme Font & Size Changer 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.
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Play all videos on YouTube with your preferred settings (size, quality, playback rate, …) without cookies using only HTML5.
Text Link Requires Restart
Allows URI texts written in webpages to be loaded by double clicks.
Menu Wizard Requires Restart Featured
Customize menus : Helps removing, moving and renaming menus and menu items
Colorize important menu for ease of use! (use Style (CSS))
Change or disable any of used keyboard shortcuts
Support: Firefox, Thunderbird and SeaMonkey
View JSON documents in the browser.
As of Firefox 33, Venkman *no longer works*, as the APIs which it needs have been removed.
Download and save videos playing on a website like youtube to your hard disk
R-kiosk Requires Restart
Real Kiosk is a Firefox extension that defaults to full screen, disables all menus, toolbars, key commands and right button menus. Alt+Home still takes you home. ...