Mozilla released a standalone Firefox Nightly test build recently that includes support for vertical tabs. Here is how it looks.
  •  Onihikage   ( @Onihikage@beehaw.org ) English
    2•3 months ago

    The very first version of Tree Style Tabs was published in… hmm…

    2007

    The shameful part is the fact that Edge-Chromium added a native tree style tabs feature over three years ago, and has been eating Firefox’s lunch. Vivaldi has had native vertical tabs for eight years! Mozilla’s leadership is asleep at the wheel.