Most Popular Extensions
Adblock Plus Featured
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).
Lightning Requires Restart Featured
Organize your schedule and life's important events in a calendar that's fully integrated with your Thunderbird email. Manage multiple calendars, create your daily to do list, invite friends to events, and subscribe to public calendars.
This add-on is not compatible with your version of SeaMonkey because of the following:
- Add-on has opted into strict compatibility checking.
Finally, an efficient blocker. Easy on CPU and memory.
NoScript Security Suite Requires Restart Featured
The best security you can get in a web browser!
Allow active content to run only from sites you trust, and protect yourself against XSS and Clickjacking attacks.
The first and only download manager/accelerator built inside Firefox!
An extension that adds direct links to download YouTube videos as MP4 and FLV. It has a simple interface and it downloads videos directly from YouTube. The extension integrates with YouTube's interface and adds a download button below the player.
LastPass Password Manager Requires Restart
LastPass, an award-winning password manager, saves your passwords and gives you secure access from every computer and mobile device.
FlashGot Mass Downloader Requires Restart Featured
Download all the links, movies and audio clips of a page at the maximum speed with a single click, using the most popular, lightweight and reliable external download managers.
YouTube High Definition is a powerful tool that will let you automatically play all YouTube videos in HD (High Definition), turn off annotations, change video player size, auto stop videos, auto mute videos, control embedded videos and much more.
Download Flash and Video Requires Restart
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.
1-Click YouTube Video Download Requires Restart
The simplest YouTube Video Downloader for all YouTube Flash sites, period.
Fight the text ads! Element Hiding Helper is a companion extension for Adblock Plus meant to make creating element hiding rules easier.
Displays a country flag depicting the location of the current website's server and provides a multitude of tools such as site safety checks, whois, translation, similar sites, validation, URL shortening, and more...
Stylish Requires Restart
Restyle the web with Stylish, a user styles manager. Stylish lets you easily install themes and skins for Google, Facebook, YouTube, Tumblr, and many, many other sites. You can even customize Firefox and other programs themselves.
FireFTP Requires Restart
FireFTP is a free, secure, cross-platform FTP/SFTP client for Mozilla Firefox which provides easy and intuitive access to FTP/SFTP servers.
Check out my new project, FireSSH!
Web Developer Requires Restart
The Web Developer extension adds various web developer tools to the browser.
ImportExportTools Requires Restart
Adds some tools to import and export folders and messages
S3.Google Translator Requires Restart
S3.Google Translator adds the power of Google Translate’s automatic translations to your browser!
It supports translation of selected text, entered phrase or whole webpage between any of 80+ languages.
New Feature: Language learning!
EPUBReader Requires Restart
With EPUBReader you can read ePub files just in Firefox. No additional software needed!