Top-Rated Extensions

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Right Click Watch Ignore

Adds "Watch Thread" and "Ignore Thread" to right click context menu in Thunderbird and Seamonkey.

Rated 3 out of 5 stars (6)
286 users

SmartWhois Launcher

This extension allows you to launch SmartWhois and perform a Whois query on the current URL. SmartWhois is a useful network information utility that allows you to look up all the available information about an IP address, hostname or domain...

Rated 3 out of 5 stars (6)
857 users

Forumzilla

Forumzilla lets you read news and blog feeds in your email application. It is similar to the feed reader built into Thunderbird, but it lets you download stories into any folder in any POP, IMAP, or local account (configurable per...

Rated 3 out of 5 stars (5)
142 users

WebPG for Mozilla

An extension which provides GnuPG/GPG/PGP related functions to Moizilla Firefox, Thunderbird and Seamonkey

Rated 3 out of 5 stars (18)
3,797 users

CSHelper

This extension packages versions of the CamStudio recorder application and the XVID Codec. It is primarily intended to be used with the screen capture feature of the Video DownloadHelper add-on, when on Windows.

Rated 3 out of 5 stars (15)
55,805 users

IE Tab + (FF 8+, 7, 6, 5, 4, 3.6, 3.5, SeaMonkey)

IE Tab + is an enhanced version of IE Tab. It supports FF 3.5 or greater, integrates IE Tab with Adblock Plus in the IE Tab engine, and synchronizes cookies between IE and Firefox. You can easily import settings from the original IE Tab into IE Tab +

Rated 3 out of 5 stars (72)
189,765 users

Clines

Clines, a little game

Rated 3 out of 5 stars (3)
124 users

TheRealURL

Get URL information: expand short URLs, get title and content type information without visiting the site.

UPDATE, AUG 2013: THIS EXTENSION IS NO LONGER SUPPORTED. The source is open - if you wish to take on the development, you're welcome.

Rated 3 out of 5 stars (7)
574 users

superbar

superaddon!

Rated 3 out of 5 stars (3)
15 users

EditCSS

Stylesheet modifier in the Sidebar.

Rated 3 out of 5 stars (12)
7,256 users

Bookmark Indicator

Shows an icon on the location bar that tells whether the current page is bookmarked.

Rated 4 out of 5 stars (1)
22 users

Duplicate Tab Blocker No Restart

Prevent duplicate tabs. Allow only one tab for a url. If you click a link that is already opened in a tab, then existing tab would be focused instead of opening a new tab. This works even across firefox windows.

Rated 3 out of 5 stars (7)
1,030 users

PreviousPage

Shows previous page on the left side

Rated 4 out of 5 stars (2)
21 users

Display mailing list header

This extension implements RFC 2369 for Thunderbird: Special mailing list header fields in the mail are parsed, and the links are displayed in the extended header view. You can click them to simply go to the archive, request help or unsubscribe.

Rated 3 out of 5 stars (6)
604 users

Hash Password Generator

Generates different passwords for each website using a choice of multiple algorithms.

Rated 3 out of 5 stars (4)
312 users

Amazing Media Browser

A Multimedia Download Tool

Rated 3 out of 5 stars (21)
687 users

Key config

This add-on provides configurable keyboard shortcuts for several actions and a dialog to customize them.
All shortcuts can be redefined in Tools -> Key settings

Rated 3 out of 5 stars (11)
2,663 users

Relaxed the HTML Validator

"Relaxed" is a HTML validator which validates HTML documents using it's own schema definitions written in Relax NG with embedded Schematron patterns.

Rated 3 out of 5 stars (5)
79 users

ALLYouTubeDownloader

ALLYouTubeDownloader extention (FLV/MP4/WebM; HD/HQ). Windows only. Works only with ALL YouTube Downloader 2.3 application or higher (versions 2.2 and lower doesn't work anymore).
Homepage: http://www.allplayer.org/youtube-to-allplayer

Rated 3 out of 5 stars (7)
116,174 users

Validaty

One Click Validator. Provides you a button to validate a page using a validator like w3c or another user defined

Rated 3 out of 5 stars (6)
1,356 users