All of the changes you make in Firefox, such as your home page, what toolbars you use, extensions you have installed, saved passwords and your bookmarks, are stored in a special folder called a profile. Your profile folder is stored in a separate place from the Firefox program so that, if something ever goes wrong with Firefox, your information will still be there. It also means that you can uninstall Firefox without losing your settings and you don't have to reinstall Firefox to clear your information or troubleshoot a problem.

How do I find my profile?

• Click the menu button , click Help and select More Troubleshooting Information.From the Help menu, select More Troubleshooting Information. The Troubleshooting Information tab will open.
• Under the Application Basics section next to Profile FolderProfile Directory, click Open FolderShow in FinderOpen Directory. A window will open that contains your profile folder.Your profile folder will open.Your profile folder will open.

Finding your profile without opening Firefox

What information is stored in my profile?

Bookmarks, Downloads and Browsing History:

• places.sqlite
  This file contains all your Firefox bookmarks and lists of all the files you've downloaded and websites you’ve visited.
• bookmarkbackups
  This folder stores bookmark backup files, which can be used to restore your bookmarks.
• favicons.sqlite
  This file contains all of the favicons for your Firefox bookmarks.

For more information, see Bookmarks in Firefox and Restore bookmarks from backup or move them to another computer.

Passwords:

• key4.db
• logins.json
  
  Your passwords are stored in these two files. For more information, see Password Manager - Remember, delete and edit logins and passwords in Firefox.

Site-specific preferences:

• permissions.sqlite
• content-prefs.sqlite
  
  These two files store many of your Firefox permissions (for instance, which sites are allowed to display popups) or zoom levels that are set on a site-by-site basis (see Font size and zoom - increase the size of web pages).

Search engines:

• search.json.mozlz4
  This file stores user-installed search engines. For more information, see Add or remove a search engine in Firefox.

Personal dictionary:

• persdict.dat
  This file stores any custom words you have added to Firefox's dictionary. For more information, see How do I use the Firefox spell checker?.

Autocomplete history:

• formhistory.sqlite
  This file remembers what you have searched for in the Firefox search bar and what information you’ve entered into forms on websites. For more information, see Control whether Firefox automatically fills in forms.

Cookies:

• cookies.sqlite
  A cookie is a bit of information stored on your computer by a website you’ve visited. Usually, this is something like your site preferences or login status. Cookies are all stored in this file.

DOM storage:

DOM Storage is designed to provide a larger, more secure, and easier-to-use alternative to storing information in cookies.

• webappsstore.sqlite
  Information is stored in this file for websites
• chromeappsstore.sqlite
  This file stores information for about:* pages.

Extensions:

• extensions
  This folder, if it exists, stores files for any extensions you have installed. To learn more about Firefox extensions and other add-ons, see Find and install add-ons to add features to Firefox.

Security certificate settings:

• cert9.db
  This file stores all your security certificate settings and any SSL certificates you have imported into Firefox.

Security device settings:

• pkcs11.txt
  This file stores security module configuration.

Download actions:

• handlers.json
  This file stores your preferences that tell Firefox what to do when it comes across a particular type of file. For example, these are the settings that tell Firefox to open a PDF file with Acrobat Reader when you click on it. For more information, see Manage file types and download actions in Firefox.

Stored session:

• sessionstore.jsonlz4
  This file stores the currently open tabs and windows. For more information, see Restore previous session - Configure when Firefox shows your most recent tabs and windows.

Window positions and dialog settings:

• xulstore.json
  This file stores the size and position of the main Firefox window and Library window, selected columns in the Library window, and expanded folders in the Bookmarks Sidebar and History Sidebar.

User preferences:

• prefs.js
  This file stores customized user preference settings, such as changes you make in Firefox Settings dialogs and in customizing toolbars (Customize Firefox controls, buttons and toolbars). The optional user.js file, if one exists, will override any modified preferences.

Containers:

• containers.json
  This file stores the details of containers used by the Container Tabs feature, including those created by extensions such as Facebook Container.

Working with profiles

• Profile Manager - Create, remove or switch Firefox profiles explains how to do things like, create a new profile, set a new default profile, and delete an old profile.
• Recover user data missing after Firefox update explains how to use the Profile Manager to switch profiles, if multiple profiles exist.
• Back up and restore information in Firefox profiles explains how to back up and restore a profile. It also explains how to move your profile information to a different location on your hard drive or to another computer.
• Recovering important data from an old profile explains how to copy files to a new profile and includes a list of files that store information useful for recovery.