Every so often, you might need to find your Firefox profile folder to do some tweaking or maintenance of your own. In the past, this has lead to diving through your operating system’s folders and after twenty clicks, finding the information you need. Since Firefox 3.6 there is a much easier way to open your profile folder, with no additional extensions installed.
To open your Firefox profile folder, go to Help in the menu bar:
Next, click on Troubleshooting Information. This will take you to the about:support information page. If you can remember, you can also visit this page by typing about:support into the Firefox address bar too.
Under Application Basics, click on the button that reads, "Open Containing Folder" next to Profile Directory, and there you go. Your Firefox profile directory should be opened up. Going to the profile location by following the folder path to it via your computer still works, but this is a much easier way to get the job done.
Hope this comes in handy next time you want to backup, tweak or change something in your Firefox profile folder.