Add-ons
Most Popular Extensions
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Flexible Identity
Requires Restart
Selects an identity based on the recipients list when sending an email
ThunderBirthDay
Requires Restart
Display birthdays from the Thunderbird addressbooks as events in Lightning.
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.
uBlock Origin
An efficient blocker. Easy on CPU and memory. New and updated filter list added.
Disable Add-on Compatibility Checks
Reinstates the extensions.checkCompatibility preference without respect to the current application version.
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.
Image Zoom
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.
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.
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
Lightbird
Extra Format Buttons
Requires Restart
Adds a font size (in pixels), strikethough, subscript and superscript buttons to Thunderbird's Compose Window.
Complete YouTube Saver
Requires Restart
Download YouTube videos in various formats including 1080p, 4K etc (DASH formats). Convert audio track from videos to MP3 or WAV, or save audio in native format (Ogg, AAC/M4A, MP3, OPUS). Save YouTube page, video, comments and subtitles to one folder
AMO Browsing for SeaMonkey
This extension makes browsing for extensions easier at addons.mozilla.org. It fixes incorrect information about some extensions being not available for SeaMonkey and adds links to the Add-on Converter where needed.
To create your own collections, you must have a Mozilla Add-ons account.
