Most Popular Extensions

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Text2Link Requires Restart

Text2Link is a simple and easy-to-use way to copy the text of a link, or to open URLs and send emails to addresses not marked-up as HTML links.

Rated 4 out of 5 stars (41)
372 users

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.

Rated 4 out of 5 stars (336)
370 users

Awesome ldapInfoShow

Show contact photo and other info from Local Dir, Addressbook, LDAP, Facebook, LinkedIn, Flickr, Gravatar etc

Rated 4 out of 5 stars (14)
366 users

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.

Rated 5 out of 5 stars (847)
363 users

Gmail Manager NG Requires Restart

Based on Gmail Manager by Todd Long. This fork is intended to a supported version of Gmail Manager since Todd appears to have gone MIA. Manage multiple Gmail accounts and receive new mail notifications.

Rated 4 out of 5 stars (109)
339 users

Zindus Requires Restart

Google and Zimbra contact sync for Thunderbird. (TB 24 and above NOT supported)

Rated 4 out of 5 stars (199)
313 users

LookOut+ Requires Restart

LookOut is a plugin which allows to interface with Microsoft's mail tools by decoding metadata and attachments encapsulated/embedded in a TNEF encoded attachment (aka winmail.dat).

This version is a fix for Seamonkey 2.*.

Rated 4 out of 5 stars (5)
308 users

Standalone SeaMonkey Mail

Use SeaMonkey as a standalone e-mail client. Set up a default browser for links opened from Mail & Newsgroups.

Rated 5 out of 5 stars (9)
301 users

SQLite Manager Requires Restart

Manage any SQLite database on your computer.

Rated 4 out of 5 stars (354)
281 users

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

Rated 4 out of 5 stars (185)
270 users

Cookies Exterminator

Auto delete cookies, localStorage and IndexedDB objects as soon as they become unused

Rated 5 out of 5 stars (17)
257 users

Download Status Bar

If you are the kind of person who likes to have total control over every aspect of your downloads, "Download Status Bar" is the add-on you are looking for.

Rated 5 out of 5 stars (437)
248 users

Spanish (Spain) ChatZilla Requires Restart

Spanish (es-ES) Language Pack for ChatZilla

Rated 5 out of 5 stars (7)
245 users

Year view Requires Restart

Year view for calendar.

Rated 4 out of 5 stars (55)
236 users

QuickNote Requires Restart

A simple note-taking extension.

Rated 5 out of 5 stars (204)
223 users

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.

Rated 5 out of 5 stars (6)
220 users

Send Filter Requires Restart

This add-on allows you run your message filters automatically on outgoing messages after sending. In other words, it's a outgoing filter for thunderbird and seamonkey.

Rated 4 out of 5 stars (38)
207 users

CuteButtons

Adds icons to buttons and/or menus.

Rated 4 out of 5 stars (94)
204 users

Contact Photos Requires Restart

Displays contact photos in the message header.

Rated 4 out of 5 stars (30)
202 users

Customizations for Adblock Plus

This extension provides various customization options for the Adblock Plus user interface.

Rated 5 out of 5 stars (15)
195 users