All About Mozilla Firefox Profile Folder and Configuration Files

Mozilla Firefox stores the configuration data and some CSS styling code in various files which can be edited to configure and customize Firefox UI. Today in this topic, we are going to tell you the file names and their location so that you can edit them easily.

Following are 3 main files which are used by Firefox:

  • prefs.js
  • userChrome.css
  • userContent.css

All these 3 files are plain text files and are stored in your Firefox profile folder. You can edit them using any standard text editor like Notepad in Windows and gedit in Linux.

Now the question comes what is this Firefox profile folder and where is it stored? Firefox saves all your personalized settings in profile folder and you can find the folder in following location:

Location of Firefox Profile Folder:

Windows 2000, XP, Vista, 7 and later:


Just copy and paste above mentioned path in RUN dialog box and press Enter. In "Profiles" folder, you'll find another folder with a name similar to "xxxxxxxx.default", where xxxxxxxx is a random string of characters.

Windows 95, 98 and Me:

%windir%\Application Data\Mozilla\Firefox\Profiles\xxxxxxxx.default\



Mac OS X:

~/Library/Application Support/Firefox/Profiles/xxxxxxxx.default/

Alternative Way:

You can also directly open Firefox profile folder using following steps:

  • Click on Firefox Menu button and select Help -> Troubleshooting Information option. You can also directly open it by typing about:support in addressbar as mentioned here.
  • It'll open Troubleshooting Information page. Now just click on "Show Folder" button given next to "Profile Folder" label.
  • It'll open Firefox profile folder directly.

Location of Firefox Customization Files:

Once you go to "Mozilla\Firefox\Profiles\xxxxxxxx.default\" folder, you'll find the above mentioned 3 files in following locations:


It is the main preferences file in Firefox which stores all the data defined by about:config page. You can right-click on the file and select Edit option to modify its content.

Path: \Mozilla\Firefox\Profiles\xxxxxxxx.default\prefs.js


This file is used to show various elements in Firefox UI. The file should be stored in a sub-folder called chrome in your profile folder. The CSS file and "Chrome" folder don't exist by default, so you'll need to create them. First create a new folder inside "xxxxxxxx.default" folder and change its name to Chrome. Now open this new Chrome folder and create a new text file userChrome.css.

Path: \Mozilla\Firefox\Profiles\xxxxxxxx.default\chrome\userChrome.css


This file is used to define web page content. Similar to userChrome.css file, this file should also be stored in sub-folder chrome in your profile folder. This file also doesn't exist by default, so you'll need to create it using similar steps as mentioned above.

Path: \Mozilla\Firefox\Profiles\xxxxxxxx.default\chrome\userContent.css

So go ahead and start customizing Mozilla Firefox web browser...

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Posted in: Mozilla Firefox

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  • is it just me or does this chrome folder not exist for some? do i need to install the lower versions of firefox for this chrome folder? reinstalled firefox used it a bit to tweak some about:config settings then was on to do this userchrome thing but didnt find nothing, and then searched whole computer for all those files and none found. am i cursed? Lol

  • VG

    ^^ Create the folder manually. New Firefox versions dont come with the folder.

  • I wanted the 'search box' gone from "new tab" page. Took some trial & error because I'm new to comp language & programs. First I look over what I have to do by opening things & making notes before I change anythng. When I make a mistake, I look at what I did & can always undo it. Success!! Thanks for the paths!! It helped ensure I was doing things right.

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