Great extension for vertical tabs. Works flawlessly, no bugs and no crappy animations like other extensions I tested. Grouping tabs by right-clicking is super useful, it's like bookmarks but better. Speaking of bookmarks, you can select tabs and bookmark all of them at once, super useful. The sections, used with Firefox Containers, are super great to separate work, school, and personal things. Unloading tabs is also a functionality that I think is super useful when you want to keep tabs in the sidebar but don't have them loaded.