Most Popular Extensions


Enigmail Featured

OpenPGP message encryption and authentication for Thunderbird and SeaMonkey.

Rated 4 out of 5 stars (184)
190,615 users

Image Zoom Featured

Adds zoom and rotation functionality for images...

Rated 4 out of 5 stars (334)
180,073 users

CompactHeader Featured

Add symbol in header plane to switch between compact and expanded view. Options to switch between one or two lines compact view, which buttons should be displayed in header pane. For Thunderbird 36 and older use version 2.0.9 (see version history)

Rated 5 out of 5 stars (170)
170,108 users

Text Link

Allows URI texts written in webpages to be loaded by double clicks.

Rated 4 out of 5 stars (291)
165,229 users

DOM Inspector

DOM Inspector is a tool that can be used to inspect and edit the live DOM of any web document or XUL application. The DOM can be navigated using a two-paned window displaying a variety of different views on the document and all nodes within.

Rated 5 out of 5 stars (65)
154,520 users

JavaScript Debugger

As of Firefox 33, Venkman *no longer works*, as the APIs which it needs have been removed.

Venkman is the code name for Mozilla's JavaScript Debugger. Venkman aimed to provide a powerful JavaScript debugging environment for Mozilla based browsers.

Rated 4 out of 5 stars (50)
151,333 users

Toolbar Buttons No Restart

Adds toolbar buttons to the customize toolbar window in several programs including Firefox, Thunderbird and SeaMonkey. Some of the buttons make commonly preformed actions quicker, others add new functionality.

Rated 4 out of 5 stars (317)
148,598 users

Bluhell Firewall No Restart

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

Rated 5 out of 5 stars (244)
143,656 users

Manually sort folders

This extension allows you to manually sort (order) your folders in the folder pane of Thunderbird or automatically sort them, but in a better way. This extension also allows you to re-order accounts in the folder pane.

Rated 4 out of 5 stars (106)
121,839 users

X-notifier (for Gmail,Hotmail,Yahoo,AOL ...)

Notifier for gmail, yahoo, hotmail, aol and more webmails.
X-notifier(aka WebMail Notifier) checks your webmail accounts and notifies the number of unread emails...
Supports : gmail, yahoo, hotmail, POP3/IMAP, facebook, twitter and more

Rated 4 out of 5 stars (1,630)
113,995 users

Signature Switch Featured

Switch the signature on/off or choose a new one from your predefined set...

Rated 4 out of 5 stars (173)
108,690 users


ReminderFox displays and manages lists of reminders and ToDo's. ReminderFox makes sure you remember all of your important dates via easy-to-use lists, alerts, and alarms, right in your browser without the need for a separate calendar program.

Rated 4 out of 5 stars (498)
105,262 users

HTTPS Everywhere

Encrypt the web! HTTPS Everywhere is a Firefox extension to protect your communications by enabling HTTPS encryption automatically on sites that are known to support it, even when you type URLs or follow links that omit the https: prefix.

Rated 5 out of 5 stars (43)
105,146 users

Theme Font & Size Changer No Restart

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 5 out of 5 stars (154)
105,145 users

Saved Password Editor

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

Rated 5 out of 5 stars (210)
101,259 users

UnMHT No Restart

UnMHT allows you to view MHT (MHTML) web archive format files, and save complete web pages, including text and graphics, into a single MHT file in Firefox/SeaMonkey.

Rated 5 out of 5 stars (220)
95,735 users


Quicktext is an extension for Thunderbird that lets you create templates that can be easily inserted into your own emails.

Rated 4 out of 5 stars (276)
94,677 users

Custom Buttons

Gives a possibility to create custom toolbarbuttons...

Rated 4 out of 5 stars (90)
91,057 users

Thunderbird Conversations No Restart

This addon provides a conversation view for Thunderbird, grouping messages together and allowing you to reply "inline" thus providing a more efficient workflow.

The latest version is compatible with Thunderbird 38+ only (see below for details).

Rated 4 out of 5 stars (401)
86,201 users


Synchronizes contacts & groups between Thunderbird or SeaMonkey and Google Contacts. Imports Facebook friends, contacts you follow on Twitter, and more.

Rated 4 out of 5 stars (205)
84,667 users