Most Popular Extensions
SeaTab-X-2 Requires Restart
Adds Firefox-style tab closers into SeaMonkey.
Fight the text ads! Element Hiding Helper is a companion extension for Adblock Plus meant to make creating element hiding rules easier.
SeaMonkey Debug and QA UI Requires Restart
Provides Additional Debug and QA UI for SeaMonkey development and testing.
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.
Header Tools Lite Requires Restart
Allows to modify the header and the source of messages
ThunderBirthDay Requires Restart
Display birthdays from the Thunderbird addressbooks as events in Lightning.
The first and only download manager/accelerator built inside Firefox!
Lightbird Requires Restart
Standalone calendar UI for Lightning
Get a faster browsing experience by blocking nasty web resources using Bluhell Firewall, the lightweight Ad-Blocker and Tracking/Privacy Protector.
Image Zoom Requires Restart
Adds zoom and rotation functionality for images...
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!
P7MON Requires Restart
Abilita la gestione alternativa degli allegati P7M
Speed Dial & Start Page with flexible layout for fast access to sites via visual bookmarks
Saved Password Editor Requires Restart
Adds the ability to create and edit entries in the password manager.
Show contact photo and other info from Local Dir, Addressbook, LDAP, Facebook, LinkedIn, Flickr, Gravatar etc
Extra Format Buttons Requires Restart
Adds a font size (in pixels), strikethough, subscript and superscript buttons to Thunderbird's Compose Window.
GNOMErunner Options Requires Restart
Allows to customize GNOMErunner theme
Flexible Identity Requires Restart
Selects an identity based on the recipients list when sending an email
A fork of PDF.js with support for SeaMonkey 2.49.x.
Return Receipt Toolbar Button Requires Restart
Allow you to add a Return Receipt button to mail compose window toolbar.