Hello,

Please take a look at: https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

1. Create a new shortcut for Firefox
2. Right click on the new shortcut and click properties
3. Under the Shortcut tab, at the end of "Target" line, add a space after "firefox.exe" followed by "-P -no-remote"
4. Create a new profile that you want to use alongside your main profile - this new profile will essentially be a "new install"

Is there a particular reason why you want to use a different Firefox to view certain HTML files?

EDIT: This new shortcut will always ask you which profile you want to use, but I think if you have the "Use selected profile without asking at startup" and use your original Firefox shortcut (without the -P -no-remote), it will use the most recently opened profile.

EDIT 2: Based on james' post below,

Actually it is firefox.exe -P -no-remote

That article is for Windows, Mac OSX and Linux. If you are using Linux when viewing a article on sumo KB then it will default for Linux. You can manually change it to another OS and Firefox version under the Customize this article on left sidebar.

See also:

• http://kb.mozillazine.org/Opening_a_new_instance_of_Firefox_with_another_profile
• https://developer.mozilla.org/Mozilla/Multiple_Firefox_Profiles

Thank you for your support,

what I really want is to associate .html files with a different firefox installation/profile so that when I click the .html file, it opens in a firefox window that is completely independent from the default firefox session I use otherwise. It would help, because I have firefox remember opened tabs, and I dont want all of them opened when I want to see just one specific saved webpage. Also, I have a lot of extensions installed, and thus starting firefox with all of them is a bit slow. When reading html files, however, I would only need 2 of all those extensions so an independent firefox could open the files faster, I suppose. I could use a different browser just for opening those files, but, I have .mht files saved by a firefox extension, and they really can be viewed best when opened in firefox... so, this is the whole story. I tried creating a shortcut with -P "profile name" -no-remote, but it only works if I drag the files on the shortcut. I cannot associate files with it. I also tried to use firefox variants like Light or PaleMoon, but they all either interfered with firefox, or was not compatible with the extensions I would need. I was wondering that perhaps creating a .bat file to open firefox with above parameters could solve the problem, as it would be possible to associate files with it, but I don't know how to program the .bat file to open the specific file I am clicking on, instead of just opening a new firefox window.

File associations are subject to how Windows works and its' limitations.

IMO, you will need to make the Profile you want associated with HTML files the default Profile. I would do that by editing the profiles.ini file to change the default Profile which is labeled as Default=1, but someone else might have a 'smoother' method. But then everything that you want to be opened in the default browser will open in Firefox with that "HTML Profile". When you're using Firefox as the default browser in Windows, it will only use the Profile labeled as the Default in the profiles.ini file when the default browser is called on to open. If that seems nonsensical, don't blame me - I have beat my head against the wall for almost 10 years over this Default browser / Default Profile "thing", every time I screw up a Profile when the default browser opens the wrong Profile, after I have been 'dicking with' multiple Profiles. Of course, I brought that on myself by having too many versions of Firefox installed and having too many Profiles.

If it was me, I would use the 2nd, slimmed down Profile and get used to using File > Open File... and drilling thru the Explorer file system to find the file I wanted to open, and open it from the Open File dialog box.

Not sure if you expect to make changes to your system with this html files, but you can also run another instance of Firefox in Sandboxie, I think what you could do is right click on any .html files on your computer and "Run Sandboxed".

You may have to tweak the browser a little so that the sandboxed version runs your slimmed down profile, but I imagine you could set it up to work the way you want.

Thank you the-edmeister, your solution is the closest to what I wanted, so I will use this for now. To summarize the solution, just for the record: 1. Use the profile manager to create a new profile: create a shortcut for firefox.exe, then type -P -no-remote (with space, without brackets) after firefox.exe in the shortcut target field (properties->shortcut->target field) 2. Set the profile you just created to default 3. go to the shortcut target field again, and change the -P -no-remote tag to: -P "name of your other profile" -no-remote 4. use the modified shortcut to start your regular firefox session

thanks again for every answers

The default profile should always be started without the -no-remote command line switch because that switch will prevent opening additional links by clicking a file in an external program (Windows Explorer).

• http://kb.mozillazine.org/Using_multiple_profiles_-_Firefox
• http://kb.mozillazine.org/Opening_a_new_instance_of_Firefox_with_another_profile
• https://developer.mozilla.org/Mozilla/Multiple_Firefox_Profiles

Of course you only need the -no-remote for the second instance and not for both instances.

Firefox 1.0 was the last major Release (yes Firefox existed before 1.0) to allow you to start a second instance with just the ProfileManager as Firefox 1.5 required MOZ_NO_REMOTE then changed to -no-remote for Firefox 2.0 and since.

Actually the -no-remote command line switch is converted to MOZ_NO_REMOTE=1 to make it possible to restart Firefox.

• http://mxr.mozilla.org/mozilla-central/source/toolkit/xre/nsAppRunner.cpp#3264