Most Popular Extensions
Send Later Requires Restart
True "Send Later" functionality to schedule the time for sending an email.
Mozilla Archive Format, with MHT and Faithful Save Requires Restart
— Open web pages saved with Internet Explorer or other browsers (MHT)
— Save many tabs, video and audio reliably, in a single ZIP file (MAFF)
— Return to the original site you saved a page from, and more!
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
Image Zoom Requires Restart
Adds zoom and rotation functionality for images...
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.
Mail Merge Requires Restart
Mass Mail and Personal Mail
The most efficient blocker for Firefox.
No ads, no tracking, and insanely faster page loads.
RefControl Requires Restart
Control what gets sent as the HTTP Referer on a per-site basis.
Saved Password Editor Requires Restart
Adds the ability to create and edit entries in the password manager.
As of Firefox 33, Venkman *no longer works*, as the APIs which it needs have been removed.
DOM Inspector Requires Restart
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.
ChatZilla Requires Restart
A clean, easy to use and highly extensible Internet Relay Chat (IRC) client.
Add-ons Manager Context Menu Requires Restart
Add more items to Add-ons Manager context menu.
VKontakte.ru Downloader (music/videos/photos @ VK) Requires Restart
Download music, videos and photos from VK.com / vkontakte.ru. One-click download, natural filenames, displaying file size and bitrate for music, downloading HD video, downloading HQ photos. No spam, no usage of your account, no spyware.
InlineDisposition changes the disposition of Content-Disposition response headers from attachment to inline; this prevents servers from forcing the browser to save a file and allows that file to be viewed in the browser, if the browser supports it.
Youtube MP3 Podcaster Requires Restart
Self contained add-on for downloading youtube videos to mp3 for easy listening on podcasting gadgets like a Zune or iPod
IE View Requires Restart
Lets you load pages in IE with a single right-click, or mark certain sites to *always* load in IE.
Thumbnail Zoom Plus Requires Restart
Shows full image when you hover over a thumbnail. Works with Amazon, Baidu Images, Bing Images, Facebook, Flickr, Google+, Google Images, IMDb, LinkedIn, Netflix, Pinterest, Reddit, Twitter, Yandex, YouTube, Wikipedia, Yahoo Images, & many more.
ReminderFox Requires Restart Featured
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.
Mail Redirect Requires Restart
Allow to redirect (a.k.a. "remail") mail messages to other recipients.