It allows you to have more control over your web browsing experience by effectively managing multiple tabs at once.

How do vertical tabs work?

Enabling the vertical tabs setting moves your open tabs from the top of your browser window (above the address bar) to the left side of the window. This allows the tabs to be displayed vertically, stacked one on top of the other, instead of horizontally.

Features

     Manage tabs and tab groups efficiently with a vertical tabs panel.
     You can now save, restore, and reorder tabs, including tab groups, using drag-and-drop functionality.
     The Vertical Tabs Panel presents your open tabs in a side-by-side layout.
     Efficiently search multiple tabs using fuzzy search.
     To save memory, you can suspend open tabs.
     Enable cross-browser cloud synchronization with a single login.
     Dark Mode Support.
     Space Backup Solution
     Save your session as a JSON file
     Cloud sync by login
     AI-powered Tab Grouping
     Group Guardian, Auto Grouping your tabs within URL matchers


 The advantages of vertical tabs

PS: Side Space is a futuristic vertical tab manager that can only be used with Firefox version 139 or above.