Blocks annoying video ads on YouTube, Facebook ads, banners and much more.
Adblock Plus blocks all annoying ads, and supports websites by not blocking unobtrusive ads by default (configurable).
The first and only download manager/accelerator built inside Firefox!
Download Flash and Video is a great download helper tool that lets you download Flash games and Flash videos (YouTube, Facebook, Dailymotion, Google Videos and more) with a single click.
The downloader is very easy to use.
The User Agent Switcher extension adds a menu and a toolbar button to switch the user agent of a browser.
United States English Spellchecker for Firefox, Thunderbird and SeaMonkey by Kevin Atkinson and Geoff Kuenning.
To enable, right-click in a multi-line text box, select "Languages", then "English (United States)".
When you find something on the web that you want to view later, put it in Pocket. It automatically syncs to your phone, tablet or computer so you can view it at any time, even without an internet connection.
Screen capture Web Page, selected region or whole browser window, edit screenshots and save the images to Local File or Google Drive. Edit screenshots in a very user-friendly interface with the different tools.
This extension prevents Google, Yahoo and Yandex search pages from modifying search result links when you click them. This is useful when copying links but it also helps privacy by preventing the search engines from recording your clicks.
Integrates location bar and search bar into one. Shows search and url suggestions. Quickly switch search engine using search keywords. Provides different auto-complete popup styles for compact displays.
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.
Open Bookmarks/History/Homepage/URL/Search in new tabs, and more utilities for tabbed browsing, including Protect/Lock/Faviconize/Unload Tab, Reload Every, Select and manipulate multiple tabs simultaneously, Tab Stacking/Coloring, etc.
Collections are groups of related add-ons that anyone can create and share.Explore Collections