Most Popular Extensions

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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).

Rated 5 out of 5 stars (5,134)
17,420,983 users

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.

Rated 3 out of 5 stars (1,830)
6,341,595 users

uBlock Origin

Finally, an efficient blocker. Easy on CPU and memory.

Rated 5 out of 5 stars (1,474)
3,863,320 users

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.

Rated 5 out of 5 stars (1,559)
2,261,553 users

DownThemAll! Featured

The first and only download manager/accelerator built inside Firefox!

Rated 4 out of 5 stars (1,755)
1,152,659 users

Download YouTube Videos as MP4

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.

Rated 4 out of 5 stars (482)
1,046,187 users

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.

Rated 5 out of 5 stars (532)
685,971 users

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.

Rated 4 out of 5 stars (388)
604,696 users

1-Click YouTube Video Download Requires Restart

The simplest YouTube Video Downloader for all YouTube Flash sites, period.

Rated 4 out of 5 stars (512)
588,789 users

YouTube High Definition

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.

Rated 5 out of 5 stars (228)
543,577 users

Web of Trust, MyWOT/WOT: Website Reputation Rating Requires Restart

Instantly know which websites to trust! WOT protects you while you browse, warning you against dangerous sites that host malware, phishing, and more.

Rated 4 out of 5 stars (1,318)
489,791 users

Element Hiding Helper for Adblock Plus

Fight the text ads! Element Hiding Helper is a companion extension for Adblock Plus meant to make creating element hiding rules easier.

Rated 5 out of 5 stars (431)
483,488 users

ImportExportTools Requires Restart

Adds some tools to import and export folders and messages

Rated 4 out of 5 stars (154)
431,537 users

Flagfox

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...

Rated 5 out of 5 stars (665)
430,402 users

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.

Rated 4 out of 5 stars (815)
412,457 users

Web Developer Requires Restart

The Web Developer extension adds various web developer tools to the browser.

Rated 5 out of 5 stars (262)
404,581 users

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!

Rated 4 out of 5 stars (938)
402,745 users

HTTPS Everywhere Requires Restart

Encrypt the web! HTTPS Everywhere is a Firefox extension to protect your communications by enabling HTTPS encryption automatically on sites that are known to support it, even when you type URLs or follow links that omit the https: prefix.

Rated 4 out of 5 stars (164)
389,428 users

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!

Rated 5 out of 5 stars (359)
374,130 users

EPUBReader Requires Restart

With EPUBReader you can read ePub files just in Firefox. No additional software needed!

Rated 5 out of 5 stars (191)
364,461 users