MultiFirefox 2.3


  1. Brief instructions to get started are here.
  2. MultiFirefox now signed to work with Gatekeeper on OS X

About MultiFirefox

MultiFirefox is a small launcher utility that allows you to run multiple versions of Firefox side-by-side.  It helps you set up multiple profiles (one or more for each version of Firefox), remembers your last launch preferences for easy launching, has auto-updating built in for when we make improvements, and is 100% open source, MIT licensed.

It is written natively in Objective-C, but was originally written in Python and wxPython.  Posted below are links to all of the pertinent downloads.

MultiFirefox has been downloaded hundreds of thousands of times since its inception, and discussed on Lifehacker and made their top downloads, was a staff pick on Apple’s downloads site, and is even used by some of the Firefox development team at Mozilla.


Older Python Release

The original source code for MultiFirefox 1.0 was released for Python and wxWidgets/wxPython.

  • rogmabi

    I just installed the new version but now when I want to start a second firefox it just brings the existing firefox forefront. Any idea? @themartorana:disqus 

  • Adam

    The newest update isn’t working for me.  I’m running OSX Lion with the latest updates.  When I open multiff, I get a list that says “Firefox” and “Firefox Profiles”.  I have one version of FF on my system.  Under profiles, I have three different ones.

    I can open one of them, but when I try to open a second one, it never opens.  I’ve tried combinations of “Firefox” + one of my profiles, and “Firefox Profiles” + one of the profiles.  It always opens the first one, but then others never open.

    Any ideas?

  • Pingback: 13个网页兼容性效果测试与验证的途径 |Ranfon·远风()

  • Yamm Software

    @themartorana:disqus  Same problem for me

  • Leocadio Tiné

     Same here. Following the thread.

  • Pingback:

  • dan

    Same here :( I’m running OSX 10.7.4 and Firefox 17.0.1.

  • Dave Martorana

    Hey guys,
    I’m slammed right now, but this is on my list of get-to-very-soon. Sorry for the slow response!

  • Dave Martorana

    Hey Dan,

    Will get to work on it ASAP. Thanks for your patience :)

  • Pingback: Jeffrey Shaw & Peter Weibel, YOUbiläums Browser (2007)()

  • Sean Hollick

    This works exactly how I want! the only trouble is my GreaseMonkey plugins are only loading in the first instance, which ever profile i chose first they load then the second they don’t. Can i fix this? The whole purpose for me is to bu able to run the same GreaseMonkey  plugins in each instance at the same time

    Any help would be appreciated.

  • Dave Martorana

    Hey Sean,

    Profiles are complete sandboxes, which means if you’re running multiple browsers with multiple profiles simultaneously, you’ll have to install the GreaseMonkey scripts in to each browser separately. From there they should be able to run in parallel.

    Hope that helps!


  • Pingback: إنشاء البيئة الأفضل لتجربة المواقع على المتصفحات المختلفة - شبكة لحبابي التقنية التطويرية()

  • Cowicide

    Any headway with this? Does this no longer work with Lion nor Mountain Lion or is there a version for them that does work? Thank you.

  • Dave Martorana


    I haven’t had time to bug-fix this – unfortunately it’s one of those “works for me” issues where I tried replicating the issue and wasn’t able to. So I need to figure out exactly _why_ the issue is happening before I can fix it.

    When you say it doesn’t open the other ones, are you trying to open the same Firefox multiple times? Or exiting the first and then trying to open the second profile?


  • Cowicide

    Thanks for the response. It works fine for me, but I’m using 10.6.8 with it and haven’t has a chance to test it with my external Mountain Lion boot drive yet. If it’s working for you, then maybe it was just a temporary glitch with a version of Lion they were using. Thanks, again!

  • Adam

    Hey Dave. I was trying to open two profiles at once — my default profile, and a second profile. It wasn’t letting that happen and no matter what I selected it was opening the same (first, default) profile.

    However, I upgraded to Mountain Lion last month and hadn’t tried the new version. I just got a second Mac with Mountain Lion, and the newest version works fine for me now, so I’m not sure what was going on…

  • NorthSea

    Brilliant. Don’t ever stop developing MultiFirefox,please!!!!!!!!!!!

  • Pingback: إنشاء البيئة الأفضل لتجربة المواقع على المتصفحات المختلفة | دردشة العراق - دردشة العراق الكتابية - شات العراق - Chat iraq()

  • Pingback: Debugging CSS in multiple browsers | Ed Price Is Hungry()

  • Pingback: How To Make Firefox Profiles Alias On Mac OSX - DarrenWasHere()

  • Pingback: إنشاء البيئة الأفضل لتجربة المواقع على المتصفحات المختلفة -

  • Sjaak

    I suppose this is for Mac only? Any programs for Windows to test different Mozilla Firefox versions (like IEtester for IE)?

  • Dave Martorana

    Hi Sjaak,

    Yeah, this is Mac only. I’m sorry I can’t point to a Windows solution, but there has to be one out there.

  • Cowicide

    Does this continue to work with Apple OS Mavericks or Yosemite betas?

  • Alan

    I just tried this with Firefox 32 and OS X Mavericks 10.9.4 and it works just fine.

  • Dave Martorana

    Yup, works on OS X – I haven’t gotten to test it on Yosemite yet.

  • Cowicide

    Thanks, Alan.

  • Pingback: إنشاء البيئة الأفضل لتجربة المواقع على المتصفحات المختلفة()

  • Ranjeet Tate

    Thanks, works with Yosemite!

  • Pingback: firefox for mac | download()

  • sabrinaqedesha

    This worked for me yesterday and was immediately helpful, but is crashing today on startup (OSX 10.9.5). I deleted and redownloaded and am having the same issue. Any suggestions? Thanks!

  • Pingback: Firefox : créer plusieurs instances à utiliser en parallèle | AEM Blog()