Most Popular Extensions

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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.

Rated 5 out of 5 stars (52)
807 users

Header Tools Lite Requires Restart

Allows to modify the header and the source of messages

Rated 4 out of 5 stars (46)
794 users

DownThemAll! Featured

The first and only download manager/accelerator built inside Firefox!

Rated 4 out of 5 stars (2,896)
773 users

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.

Rated 3 out of 5 stars (100)
747 users

Lightbird Requires Restart

Standalone calendar UI for Lightning

Rated 4 out of 5 stars (21)
667 users

P7MON Requires Restart

Abilita la gestione alternativa degli allegati P7M

Rated 5 out of 5 stars (3)
660 users

ThunderBirthDay Requires Restart

Display birthdays from the Thunderbird addressbooks as events in Lightning.

Rated 4 out of 5 stars (97)
629 users

Bluhell Firewall

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

Rated 4 out of 5 stars (497)
625 users

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!

Rated 4 out of 5 stars (1,067)
617 users

Extra Format Buttons Requires Restart

Adds a font size (in pixels), strikethough, subscript and superscript buttons to Thunderbird's Compose Window.

Rated 4 out of 5 stars (19)
614 users

Saved Password Editor Requires Restart

Adds the ability to create and edit entries in the password manager.

Rated 5 out of 5 stars (389)
602 users

Image Zoom Requires Restart

Adds zoom and rotation functionality for images...

Rated 4 out of 5 stars (355)
600 users

Speed Start

Speed Dial & Start Page with flexible layout for fast access to sites via visual bookmarks

Rated 5 out of 5 stars (80)
584 users

PDF Viewer for SeaMonkey

A fork of PDF.js with support for SeaMonkey 2.49.x.

Rated 5 out of 5 stars (3)
557 users

Flexible Identity Requires Restart

Selects an identity based on the recipients list when sending an email

Rated 4 out of 5 stars (39)
488 users

GNOMErunner Options Requires Restart

Allows to customize GNOMErunner theme

Not yet rated
475 users

SeaMonkey Debug and QA UI Requires Restart

Provides Additional Debug and QA UI for SeaMonkey development and testing.

Rated 3 out of 5 stars (3)
469 users

Return Receipt Toolbar Button Requires Restart

Allow you to add a Return Receipt button to mail compose window toolbar.

Rated 5 out of 5 stars (20)
448 users

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.

Rated 3 out of 5 stars (47)
422 users

Simple Locale Switcher Requires Restart

An easier management of the user interface language

Rated 5 out of 5 stars (14)
413 users