The best tab manager there is! What a life-saver!

After many years of using Firefox and other browsers, Tab Stash is the first extension that's made it possible for me to keep the number of tabs I have open under control. Its UI is thoughtfully designed to make common actions take as few clicks as possible, in contrast to using the browser's built-in tools. This extension is as indispensable as uBlock Origin. Thanks to the author, Josh!

Amazing for research - has completely optimised my workflow! Now I cant live without it. The recent sub-groups update is perfect for organisation too.

If you've come from Google Chrome to here and are trying to find a grouping extension that's similar, this one is! Instead of grouping them in the top bar, you'll have a little sidebar. BUT, the important thing is that it will let you close out of tabs on your main slider without actually deleting them. So, if you don't like having a bunch of windows open or tabs up on your slider, you won't have to!! You can even open one tab at a time or the entire group. An absolute lifesaver for me :)

This extension is the perfect marriage between tab mgmt and bookmarks. This should be a default Firefox feature

Great add-on. Specially useful for managing multiple sessions on a single site, such as Gmail.

searching for tab outliner alternative in firefox, and this is it(much better than tab outliner in my work flow)