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Can I run Firefox Quantum and Firefox 54 side by side on a Mac?

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  • Last reply by cor-el

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I use Firefox because I love the tools that add-ons provide. I don't want to install quantum only to discover that it doesn't serve my purposes. I've fine-tuned this browser to do a lot and I don't want to start over. I've seen suggestions for using Firefox portable on a USB, but as far as I can see, there is no portable for a Mac. I'd like to keep both for a while, then make up mind. I'm hoping there's a simple solution for this. I know I'm not the only one who doesn't want to give up their add-ons.

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Yes, but it's tricky.

Each version of Firefox needs to run using its own profile.

When I run the browser like that, I use a batch file command to launch Each Firefox version separately.

Example (one line); C:\PROGRA~1\MOZILL~1\firefox.exe -no-remote -new-instance -new-window -P Firefox_v_57

Usage: C:\PROGRA~1\MOZILL~1\firefox.exe [ options ... ] [URL]
      where options include:
 -h or -help        Print this message.
 -v or -version     Print Firefox version.
 -P <profile>       Start with <profile>.
 -migration         Start with migration wizard.
 -ProfileManager    Start with ProfileManager.
 -no-remote         Do not accept or send remote commands; implies -new-instance.
 -new-instance      Open new instance, not a new window in running instance.
 -UILocale <locale> Start with <locale> resources as UI Locale.
 -safe-mode         Disables extensions and themes for this session.
 -console           Start Firefox with a debugging console.
 -jsconsole         Open the Error console.
 -browser           Open a browser window.
 -new-window  <url> Open <url> in a new window.
 -new-tab     <url> Open <url> in a new tab.
 -preferences       Open Options dialog.
 -search     <term> Search <term> with your default search engine.
 -setDefaultBrowser Set this app as the default browser.
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Installing multiple versions on Mac OS X is basically dragging the Firefox application out of the DMG file to the desktop and rename the folder. You can drag the renamed Firefox application folder to the Applications folder like you would normally install Firefox.

You need to use the terminal to create a new profile for that version. Firefox also comes with the about:profiles page that has a button to create a new profile. Make sure that no profile is selected as Default=1 to make the Profile Manager show when you start Firefox. You can check that in the profiles.ini file.