[alexvoda]

But it has 2 features that are unique:

- You can hide the titlebar/tab-bar at the top therefore maximizing vertical space

- It can be set to either be sticky (always open) or auto-collapse into a thin icons-only vertical toolbar.

The grouping functionality in Edge is inherited form Chrome without improvements.

The grouping functionality in Firefox with TreeStyleTabs or Sidebery is unmatched but this is all implemented by extensions and Firefox abandoned a lot of interface customizability when it abandoned XUL extensions. (you can theoretically do it by hacking userchrome, but it's buggy)

With old XUL extensions, TreeStyleTabs actually had the option to hide the tab-bar. And you also had the option to move the window controls to one of the toolbars.

Vivaldi does have the option to use vertical tabs but you are left with a titlebar you can't hide.