Cleaning a Firefox Profile

I occasionally like to clean my Firefox profile. I test quite a few extensions, and play around a bit, so every once in a while, I just want to clean up. This method has worked rather well for me over the years. Essentially I imported my Netscape 4 profile into Netscape 7, then Mozilla App Suite, then split into Firefox and Thunderbird, so essentially I have data in there that’s several years old. I thought I’d share what I do, and why I do it, in hopes that perhaps someone else would benefit.

These directions were drafted with Firefox 1.5 as a reference point, for older or newer releases the directions may not work (for example if you use a Firefox build with “Places”).

A word of advice:

For the record, this is at your own risk, back up before you touch anything. Backup by copying The Firefox directory as mentioned in respective location below (a directory above Profiles). You’ve been warned.


You may want to start out by going to the Bookmarks menu and selecting “Manage Bookmarks”. Then cleaning out and organizing your bookmarks, if you want to keep them in your new profile. It’s a good habit to get into.

The first real step I do is visit my profiles directory:


C:\\Documents and Settings\\[Windows Username]\\Application Data\\Mozilla\\Firefox\\Profiles\\

Mac OS X

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

Your profile will be a directory with a salted name. Something like xxxxxxxx.default. Those x’s are random characters.

Because I only have 1 real profile (and one for dev purposes of which I choose to preserve nothing), I like to rename mine to something else. As far as I’m concerned this one is dead to me. I’m going to also get rid of the profiles.cfg and pluginreg.dat files in the Firefox Folder (up above profiles), then run Firefox and create a new profile on prompt. If you have multiple profiles you wish to leave untouched you would be better off using firefox.exe -profilemanager in the command prompt and simply creating a new profile.

Ok, so now we have this really clean new profile, and that old crusty one with lots of junk. Well, I want some of my stuff in my new clean profile, but only certain things. So here’s a breakdown of what I do, pick and choose as you want. Obviously the less you bring over, the better.

Only perform the following when Firefox is not running.

Simply copy the bookmarks.html file from the old profile into the new profile.

Cookies (stay logged in with all your sites)
I like to carry these over, since I like being logged into certain sites (forums and such). Just copy the cookies.txt file from the old profile into the new profile. If you open the file up in a text editor you can delete a line or two (get rid of those old cookies, or just to satisfy that tin-foil-hat feeling). Just be careful if you do.

I also like to keep my stored passwords (nothing important, just those news sites, and other silliness that I don’t feel like entering each and every time). Password Manager is great for that. The files you want to copy over are: cert8.db, secmod.db, key3.db, signons.txt.

My recommendation on Extensions is to visit (Google for the ones you can’t find) and re-download. The reason I prefer to do that rather than move them over, is because some just seem to stubborn to use the update service, and that leaves me with some old extensions. Also, in this process I typically realize there are one or two that sounded like great ideas, but I just never really used them. Less extensions means less chances for a memory leak. That’s always a good thing.

Just copy the search.rdf file and searchplugins directory over.

Final Notes

This process typically takes me about 5-10 minutes (mainly depending on if I cleanup my bookmarks and cookies). Overall not bad. Gets rid of the crud that tends to accumulate over time, and keeps things pretty lean. This is also pretty useful if you encounter some profile corruption or other ugliness, especially if your one of us trusting soles who occasionally run nightlies from the trunk.

If you do it all correctly, you get a nice clean profile, but still keep your important data. Cache and autocomplete list will rebuild pretty quickly as you use the profile. I’ve found this technique is great for reviving that profile that’s just littered with garbage from various things I’ve done, and extensions I’ve tried.

Hopefully this helps someone.

33 replies on “Cleaning a Firefox Profile”

Good post, very useful for folks who like to mess with stuff and install tons of extensions.

BTW, don’t you migrate your preferences as well? If I relied on the default prefs.js, not only would I have to set all my options like tabbed browsing, download actions etc. again, but I would also be back to dismissing every single silly dialog about sending data, secure connections etc. I also have hell of a lot preferences for the extensions.

However, copying over the old prefs.js also doesn’t seem like a good idea, since it’s part of the mess we’re trying to get rid of. So I once started with the default preferences and while getting my Fx to behave like it used to, I added every single pref I changed to the user.js. Now I have a clean set of preferences I use every time when tidying up my profile.

Oh, and I even made a batch file to do most of the work for me.

@Ancestor: I keep prefs.js out intentionally because most of the garbage that collects is in prefs.js (you’d be suprised how much a few extensions can throw in there). That’s a good part of the mess we’re trying to clean up.

Regardless, yes you can copy it over. And even open it in a text editor to get rid of the junk in there.

Though for most users, they don’t configure many prefs, and can quickly adjust them in a few seconds using the prefs UI.

How can you manually move the extensions over anyway when most of them use cryptic folder names? I’ve wasted time drilling thru them but I’m not going thru that again. Lots of times ext. authors don’t undate anyway come new FF update time…

If there is a decipherer for this, I’d prolly buy the dang thing. Thx.

Instead of writing
C:\Documents and Settings\[Windows Username]\Application Data\Mozilla\Firefox\Profiles\
you can write

@BillyG: It’s intentionally cryptic, to ensure they are unique (they are GUID‘s). No way to go backwards since they aren’t based on the filename. The only way is for you (or a software product) to go through them. This is how naming collisions are avoided.

The way I handle the extension problem is as follows:

When installing extensions, always save the .xpi file to a folder first before installing.

Make sure this folder containing the XPI files always represents a current list of all desired plugins, i.e. if you decide you don’t want to use foo, delete foo.xpi.

After creating the new profile and copying over bookmarks, run firefox and open up the (blank) extension manager.

Highlight all the XPI files in explorer and drag/drop them onto the extension manager. (You can drag/drop them onto the main firefox window but I find that this only works if there’s only one file — the extension manager window seems to support having multiple files dropped on it.)

The extensions will now all mass install in one step. Restart firefox and hit the check for updates button to look for anything with a higher version.

Using this method it’s easy to keep a set of standard extensions that you always use, without having to manually find and download them each time.

Crear un perfil nuevo en Firefox…

El autor explica en inglés los pasos a seguir para crear de forma rápida y sencilla un perfil nuevo en Firefox, eliminando la basura instalada anteriormente pero manteniendo los datos importantes, como son los Bookmarks (bookmarks.html), Cookies (coo…

Nice article.

I follow another version of this profile cleaning scenario. I just save user.js for the basic Firefox settings, bookmarks.html for bookmarks and chrome directory in profile folder if I have visual adjustments.

Thanks very much for this article — very helpful, and I was able to clear up the problem I was having with Yahoo email pages not formatting correctly!

Understood Robert, hence my last sentence but I guess if I just did as Asteko says (minus the bookmarks since all mine are in a account). If I ever get bogged down, I’ll give that a shot. Also, thx for mentioning about dropping xpi’s into the dl mgr, all these years and I’ve never known that lol. Of course my mgr just gives me the (desired) notice box when done (besides the extra tab that it temporarily uses) so I need to tweak that when the time comes. Thx.

Is there a way to copy over the whitelist for extension installs?
It’s a little pain to add all the pages to the whitelist again when installating my twenty something extensions.

You can keep form history (very useful) by copying formhistory.dat
If **** goes in there, just press SHIFT DEL to delete the unwanted entry from the drop down menu. 🙂

Thanks for the info – I just reinstalled Firefox and now my web based mail says I can’t run script….do you know how I can turn this on
thanks in advance

Just remember to keep the old profile for a day or two… just in case you need to move stuff over.

The one thing I have issues with is my Greasemonkey and Stylish scripts. While you can find the GM scripts in a folder in your profile, Stylish scripts aren’t anywhere I can find.

Ah well… copy and paste works.

[…] If you regularly delve into your Firefox profile, you realise that after a while it starts to get a little cluttered. If you’ve ever wanted to clean it out but were afraid of losing your settings then Robert Accettura might have the solution. Lifehacker notes that this will require you to reinstall your extensions but, as they point out, this is probably the cause of most of the clutter. […]

Just as a note to everyone and anyone in particular…

I installed and FF wouldn’t run period…

Point-blank, EOF…

To tell you that this pissed me off is an understaement. I usually and regualarly update FF and for it to stop working, just hanging in my task manager, not showing me any love at all 😡

-profilemanager works, but then I lost my bookmarks (which I happen to have on another box, I learned that lesson quickly!) :mrgreen:

Thanks on that, but just out of curios – what are ALL of the switches that can be used with FF, are they listed somewhere in partic. ular?

good stuff Robert.
..I’d add hostperm.1, which stores allowed web sites for popups & software installation.

cool stuff roberts how to clean cache of all user profiles
C:\Documents and Settings\usr\Local Settings\Application Data\Mozilla\Firefox\Profiles

have been trying this from long time cant do it can clean cache in the present default profile.

Any help is appreciated

[…] Cleaning a Firefox Profile I occasionally like to clean my Firefox profile. I test quite a few extensions, and play around a bit, so every once in a while, I just want to clean up. (tags: backup browser extensions firefox windows osx useful tutorials) […]

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Very useful, thanks! Does anyone know how to do this in Firefox 3? Are the files the same?

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Any updates for Firefox 3 on this? Best I can tell, Firefox 3 doesn’t use bookmarks.html now that it’s switched to places for handling this data. With that change in mind, I can’t help but wonder what else has changed. Any advice?

Seems like a batch file could be created to copy the necessary files stated above, elsewhere, then delete all contents, then copy them back in making it a far quicker process… I may look into it, but if anyone else writes one, let us know 🙂

Thanks – firefox been crashy lately..

scripted this up – it now lives here:

~/Library/Application Support/Firefox/Profiles



[[ -n $old && -d $old ]] || { echo old dir \”$old\” DNE; (( err++ )); }
[[ -n $new && -d $new ]] || { echo new dir \”$new\” DNE; (( err++ )); }
(( err )) && exit $err;

for file in bookmarks.html cookies.txt cert8.db secmod.db key3.db signons.txt search.rdf searchplugins
echo Copying over $file
[[ -f $old/$file ]] && cp -v $old/$file $new/
[[ -d $old/$file ]] && cp -rv $old/$file $new/

echo ‘/Applications/ -profilemanager’

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