Most Popular Extensions
YouTube Video Download and Convert is the powerful add-on that lets you collect all media information available on YouTube. Advanced power panel lets you download, preview, play with and convert all media right inside Firefox.
The entire page will be fading to dark, so you can watch the video as if you were in the cinema.
Play YouTube™ Videos in Flash or HTML5 Player
Notifier for gmail, yahoo, hotmail, aol and more webmails.
X-notifier(aka WebMail Notifier) checks your webmail accounts and notifies the number of unread emails...
Supports : gmail, yahoo, hotmail, POP3/IMAP, facebook, twitter and more
Displays the Exif and IPTC data in local and remote JPEG images.
Easy and convenient screenshot tool. Allows you to make screenshots of any selected area (video and flash too), edit and upload it to server.
when activated, interrupts the built-in download manager to direct links to IDMan (Internet Download Manager)
Block sites containing pornography, or any other kind of material, based on simple keyword lists.
A new options button
Can now play embedded video if they are in the page
hls.js version can be selected in the options
Point & click to forbid/allow any class of requests made by your browser. Use it to block scripts, iframes, ads, facebook, etc.
Add price history charts and price watch features to Firefox when viewing product pages on Amazon. Use it to make informed purchasing decisions and to receive price drop alerts via email, Twitter, or RSS feed.
Save anything on the web to OneNote. Clip it to OneNote, organize and edit it, then access it from any device.
Makes every page (or only pages that you want) to have light text on dark background. Exact colors are customizable.
Accelerate your SEO efforts on the fly. SEOquake is a free plugin for browsers that provides you with key SEO metrics for a specific page, along with other useful tools such as SEO Audit and many others.
Flash Video Player for Facebook™ is a powerful tool that will let you choose Flash video player as default Facebook video player.
HTML Validator is a Mozilla extension that adds HTML validation inside Firefox and Mozilla. The number of errors of a HTML page is seen on the form of an icon
Until Firefox 56, use 0.974 (other versions)
For Firefox 57, see Web Extensions below