Vertical tabs in firefox

Use the hotkey (Ctrl+Shift+V), the VTR icon somewhere in the right top corner (via default) or Firefox's default sidebar icon and switch in the sidebar header's dropdown menu to Vertical Tabs Reloaded. Features: arranges tabs vertical.

1. Which browsers have vertical tabs?
2. How do I rotate a tab in Firefox?
3. Why can't I turn on vertical tabs?

Which browsers have vertical tabs?

Microsoft has added vertical tabs as a native feature to its Edge browser, so you'll need no extensions if you use this app to surf the web.

How do I rotate a tab in Firefox?

The Tab Rotator can be started and ended either by pressing Shift+F11 or by clicking on the Tab Rotator Icon, once it is added to the User Interface. The time interval after which the next tab should be shown, can by adjusted via the Addons Options-Page.

Why can't I turn on vertical tabs?

Perhaps you've hidden the button. Click Options (the three vertical dots at the top right), then Settings, then Appearance. The switch to display the vertical tabs button should be there.