Back to Top is a Firefox extension that helps you navigate long pages. Basically, it adds two items to the context menu (right click), toolbar and statusbar.
TapScrolland
Scroll To Top
Initially developed for Firefox only, Minimem now can reduce the memory footprint of any application. It runs in the background and can be set up to optimize as many proceses as youd like, using a very intuitive graphical interface.
CleanMem 
TreeClicks is a free Chrome & Firefox shopping extension that receives advertising fee for bringing you in as a customer and uses it for planting trees.
If only 1% of all shoppers are using TreeClicks, millions of trees could be planted.
Blocked content in your country? Don't want your child to see your browsing history? Splendid Browser Manager has you covered. Just create separate instances for all your needs! Are you a social media marketer? SEO specialist?
Firefox Multi-account ContainersSlim vertical button to toggle Firefox's (57+) sidebar on/off, on the left of browser. Firefox has native sidebar but no native switch to be touched on the edge of browser. This userChrome script provides experience like All-in-One Sidebar.
All-in-One Sidebar
An Firefox addon to supress HTTP header's referer, to protect some privacy and try not breaking the web.
RefControland
Smart Referer
Unfortunately, not all sites are suitable for most users. Up button makes it easy to navigate the page - to climb to the top is now possible in a single click. The main function of the expansion - the addition of the "upstairs" on any website.
TapScrollandScroll To Top
Automated website layout testing service. Get a free report of your sites cross-browser problems.
BrowserStackand
Browserling
Personas are free, easy-to-install "skins" for Firefox. Personas Plus extends that built-in functionality to give you even more control and easier access to new, popular, and your own favorite Personas.
VivaldiFoxand
Add Water
PasswordFox is a small password recovery tool that allows you to view the user names and passwords stored by Mozilla Firefox Web browser. By default, PasswordFox displays the passwords stored in your current profile, but you can easily select to watch the passwords of any other...
ChromePassand
OperaPassView
WebBrowserPassView is a password recovery tool that reveals the passwords stored by the following Web browsers: Internet Explorer (Version 4.0 - 9.0), Mozilla Firefox (All Versions), Google Chrome, and Opera.
ChromePass
Displays the list of the latest files that you downloaded with Firefox: URL, Filename, Referrer, MIME Type, File Size, Start/End Time,and more...
Enterprise browser migration and multi-browser management specialists. Manage and secure Internet Explorer, Chrome, & Firefox at global scale.
CookiErazor automatically removes cookies when they are not needed anymore. For a whole session or permanently can be easily set on a per-site basis.
Cookie AutoDelete
A browser extension that lists your live followed streamers and sends notifications when they start a new stream.
A browser extension that enhances the reading experience on online manga readers by displaying full chapter scans, tracking reading progress, and highlighting scored content.
Kotatsuand
MANGA Plus
Extension to pause other audio and video sources if audio is playing on the active tab with automatic resume.
This was posted over reddit a few months ago, Apparently Ad Blockers are not allowed on Youtube. Is this a new thing they've implemented? and judging by all the recent comments and posts all over r/youtube, this change was just rolled out on a larger scale.
uBlock Origin
Displays how many tabs are open. The count includes tabs from all windows. Also indicates how many tabs actually have content loaded in them – for example, after restarting Firefox.
Tab Stashand
Tabs Outliner
The ultimate dark and white themes for Firefox!.
VivaldiFoxandAdd WaterSimple-URL-Shortener - url shortener written in php (with MySQL) with history by users with great javascript functions
Cookie-Editor is a browser extension focused on productivity that helps you manage your cookies with the least amount of clicks possible. You can access the list of all the cookies on the current page, create or modify an existing cookie and delete a cookie in a maximum of three...
A collection site of Firefox userchrome themes, mostly from FirefoxCSS Reddit community.
Text Link, Allows URI texts written in webpages to be loaded by double clicks.
