Most Popular Extensions
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DownThemAll! Featured
The first and only download manager/accelerator built inside Firefox!
Disable Add-on Compatibility Checks
Reinstates the extensions.checkCompatibility preference without respect to the current application version.
ThunderBirthDay Requires Restart
Display birthdays from the Thunderbird addressbooks as events in Lightning.
Flexible Identity Requires Restart
Selects an identity based on the recipients list when sending an email
Saved Password Editor Requires Restart
Adds the ability to create and edit entries in the password manager.
Folderpane Tools Requires Restart
Allows for customization of the folder pane. Accounts can be rearranged and the startup folder can be chosen.
SeaMonkey Debug and QA UI Requires Restart
Provides Additional Debug and QA UI for SeaMonkey development and testing.
Theme Font & Size Changer for ThunderBird
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.
User Agent Switcher Requires Restart
The User Agent Switcher extension adds a menu and a toolbar button to switch the user agent of a browser.
Easiest YouTube Video Downloader
This Addon simply adds a dropdown button that lets you download YouTube Videos in various Formats. Download YouTube Videos in FLV, 3GP, MP3, MP4, 720p, 1080p in a single click.
Session Manager
Session Manager saves and restores the state of all or some windows - either when you want it or automatically at startup and after crashes. It can also automatically save the state of open windows individually.
Bluhell Firewall
Get a faster browsing experience by blocking nasty web resources using Bluhell Firewall, the lightweight Ad-Blocker and Tracking/Privacy Protector.
Speed Start
Speed Dial & Start Page with flexible layout for fast access to sites via visual bookmarks
Extra Format Buttons Requires Restart
Adds a font size (in pixels), strikethough, subscript and superscript buttons to Thunderbird's Compose Window.
FireFTP Requires Restart
FireFTP is a free, secure, cross-platform FTP/SFTP client for Waterfox which provides easy and intuitive access to FTP/SFTP servers.
Check out my new project, FireSSH!
Quote Colors Requires Restart
Quote Colors allows you to select text and background colors of different quote levels which are applied when reading or printing mail/news messages. Additionally, you can choose between graphical and traditional plain text quoting display mode.
Return Receipt Toolbar Button Requires Restart
Allow you to add a Return Receipt button to mail compose window toolbar.
Cookies Exterminator
Auto delete cookies, localStorage and IndexedDB objects as soon as they become unused
To create your own collections, you must have a Mozilla Add-ons account.