Most Popular Extensions
Replace video player with Firefox native video player
ReminderFox Requires Restart
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.
Forecastfox (fix version) Requires Restart
Get international weather forecasts from AccuWeather.com and display them in any toolbar or statusbar with this highly customizable and unobtrusive extension.
Now Available for: Firefox, Thunderbird and SeaMonkey!
KeeFox Requires Restart
Simple and secure password management. Login automatically, never forget another password, stay in control of your passwords and improve their security. Powered by the world-renowned KeePass Password Safe.
Mail Merge Requires Restart Featured
Mass Mail and Personal Mail
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).
Confirm-Address Requires Restart
Confirm E-mail address before sending mail
Google Calendar Tab Requires Restart
Adds the Google Calendar web interface as a new tab directly into Thunderbird. Creating and viewing events works just as it would in a browser like Firefox
FoxClocks shows times around the world - or just your local time - at the bottom of your browser. It deals with daylight saving time so you don't have to.
Exif Viewer Requires Restart
Displays the Exif and IPTC data in local and remote JPEG images.
Google Docs Viewer (PDF, DOCX, PPTX, XLSX, etc...) Requires Restart
View publicly-accessible PDF, DOCX, PPTX, XLSX, among other files online with Google Docs by only 2 clicks. Click as usual for your default viewer. Support bookmarked URLs. Security and your explicit viewing intention are always honored.
Custom Buttons Requires Restart
Gives a possibility to create custom toolbarbuttons...
Remove Duplicate Messages Requires Restart
If you have duplicate messages (e.g. from merging folders or downloading messages several times) you can use this tool to find and remove them from the selected folder and its subfolder by rightclicking on a folder and choosing "Remove duplicates..."
ProfileSwitcher Requires Restart
It adds some options to launch easily other profiles and the Profile Manager.
Ad Blocker lets you block all ads, tracking & malware from the web world. It is an effective solution to browse the web without offensive and annoying ads you hate to see.
rikaichan Requires Restart
Japanese to English/German/French/Russian dictionary. Just hover the mouse on top of a word, and a popup appears. Automatically de-inflects verbs and adjectives. Detailed kanji view...
Copy Plain Text 2 Requires Restart
Copies text without formatting
Mail Redirect Requires Restart Featured
Allow to redirect (a.k.a. "remail") mail messages to other recipients.
Stationery Requires Restart
Extension to mimic Outlook Express Stationery.
Allow you to use HTML files as templates for mail. Also allow custom template in replies or forwarded mail!