Most Popular Extensions

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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.

Rated 5 out of 5 stars (1,125)
47,864 users

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.

Rated 4 out of 5 stars (490)
47,556 users

Mail Merge Requires Restart Featured

Mass Mail and Personal Mail

Rated 5 out of 5 stars (147)
46,948 users

FoxClocks

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.

Rated 4 out of 5 stars (315)
46,519 users

Exif Viewer Requires Restart

Displays the Exif and IPTC data in local and remote JPEG images.

Rated 4 out of 5 stars (86)
43,089 users

Toolbar Buttons

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 (323)
42,166 users

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

Rated 4 out of 5 stars (81)
41,864 users

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.

Rated 4 out of 5 stars (59)
40,932 users

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..."

Rated 4 out of 5 stars (136)
38,908 users

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...

Rated 5 out of 5 stars (112)
34,641 users

Rikaichan Japanese-English Dictionary File Requires Restart

This is a dictionary file add-on for the Rikaichan extension.

Rated 5 out of 5 stars (9)
32,205 users

LookOut (fix version) Requires Restart

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

Rated 4 out of 5 stars (12)
32,023 users

Clippings Requires Restart

Save frequently-entered text for pasting later.

Rated 4 out of 5 stars (192)
31,697 users

Mail Redirect Requires Restart Featured

Allow to redirect (a.k.a. "remail") mail messages to other recipients.

Rated 4 out of 5 stars (124)
30,775 users

FireTray Requires Restart

A system tray extension for Linux and Windows, allowing to set up custom icon, hiding to tray instead of closing, display the number of unread messages in mailing applications, and other features ...

Rated 4 out of 5 stars (254)
30,690 users

Copy Plain Text 2 Requires Restart

Copies text without formatting

Rated 5 out of 5 stars (83)
30,642 users

Classic Toolbar Buttons

'Classic Toolbar Buttons' add-on restores old toolbar button ui (known from Fx 4-7s small view, Fx 4-12s large view & Tb 5-14) for current Firefox, Thunderbird and Seamonkey versions.

Beta builds on versions page!

Rated 5 out of 5 stars (132)
28,977 users

AttachmentExtractor Requires Restart

Extracts all attachments from selected messages and then can delete, detach or mark-read.

Rated 4 out of 5 stars (163)
28,387 users

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!

Rated 4 out of 5 stars (101)
27,891 users

PrintingTools Requires Restart

Adds some options to print messages and addressbooks

Rated 4 out of 5 stars (24)
27,540 users