I have a MacBook Air (Mojave, 10.14.6) and for Testing reasons I need to be able to have several instances of firefox running with different profiles each. At the same time.

How can I achieve this?

  • Different user accounts and switch between them?
    – Solar Mike
    Mar 20, 2020 at 8:39
  • I need two instances of firefox running. Like in one window (the thing I can change position with, with the red-yellow-green dots on the upper left) a firefox instance with profile1 is running, and in a different window a firefox instance with profile2 is running. At the same time.
    – Alex
    Mar 20, 2020 at 8:53
  • you can copy one in a folder and run one from DMG. not sure if they can make different folders in ~/Library/Cache.
    – anki
    Mar 20, 2020 at 10:28
  • What do you mean to copy "one" into a folder? One what? And what is a DMG?
    – Alex
    Mar 20, 2020 at 10:35
  • I believe there is a way to run several copies of app, generally, by making copies of the app. I got an error with firefox. Maybe if you use a different profile in the command line, you would have success. You select what profile you want to by starting firefox from the command line. developer.mozilla.org/en-US/docs/Mozilla/Command_Line_Options command line options: /Applications/Firefox.app/Contents/MacOS/firefox --help Mar 20, 2020 at 22:02

1 Answer 1


If you mean launching a new instance via Terminal, you can use this:

/Applications/Firefox.app/Contents/MacOS/firefox -no-remote -P "NAME_OF_YOUR_PROFILE"

If you just use the -p option it should open the Profile Manager which should let you select a profile via the GUI, but was always buggy for me (broken blank tabs).

More documentation on the firefox command line options can be found here.

  • Note that if the profile name doesn't exist yet, Firefox won't create it automatically. It will show the profile picker GUI, and you can create a new profile. If you pass the name of an existing profile, Firefox will load it, even with -P specified. As to what --no-remote does exactly, it's somewhat complicated. Jul 2 at 18:33

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