Firefox Portable Launcher
Copyright 2004-2017 John T. Haller of


This software is OSI Certified Open Source Software. OSI Certified is a certification mark of the Open Source Initiative.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

The Firefox Portable Launcher allows you to run Firefox from a removable drive whose letter changes as you move it to another computer. The browser and the profile can be entirely self-contained on the drive and then used on any Windows computer. Specific configuration changes are made to the chrome.rdf so that your extensions will still work as the drive letter changes.

This code is released under the GPL. Within the FirefoxPortableSource directory you will find the code (FirefoxPortable.nsi) as well as the full GPL license (License.txt). If you use the launcher or code in your own product, please give proper and prominent attribution.

By default, the program expects the following directory structure:

-\ <— Directory with FirefoxPortable.exe
+\plugins\ (optional)

The above files may also be placed in a FirefoxPortable directory with the FirefoxPortable.exe launcher a directory above that.

It can be used in other directory configurations by including the FirefoxPortable.ini file in the same directory as FirefoxPortable.exe and configuring it as detailed in the INI file section below.

The Firefox Portable Launcher will look for an ini file called FirefoxPortable.ini within its directory. If you are happy with the default options, it is not necessary, though. There is an example INI included with this package to get you started within the Other\Source directory. Note that it will not work from this location as it must be placed in the same directory as FirefoxPortable.exe. The INI file is formatted as follows:


The FirefoxDirectory, ProfileDrectory, SettingsDirectory and PluginsDirectory entries should be set to the *relative* path to the directories containing firefox.exe, your profile, your plugins, etc. from the current directory. All must be a subdirectory (or multiple subdirectories) of the directory containing FirefoxPortable.exe. The default entries for these are described in the installation section above. The FirefoxDirectory as well as the path provided with a 64 appended will be checked for the 32-bit and 64-bit versions of Firefox respectively.

The FirefoxExecutable entry allows you to set the Firefox Portable Launcher to use an alternate EXE call to launch firefox. This is helpful if you are using a machine that is set to deny firefox.exe from running. You’ll need to rename the firefox.exe file and then enter the name you gave it on the firefoxexecutable= line of the INI.

The AdditionalParameters entry allows you to pass additional commandline parameter entries to firefox.exe. Whatever you enter here will be appended to the call to firefox.exe.

The LocalHomepage entry allows you to set Firefox Portable to use a local file on your read-only disc (CD/DVD/etc) as your homepage when running in Live mode. It’s not necessary for use on regular drives (the launcher handles portablizing your homepage path). The file must be a path relative to the launcher. If you were to set it to a file in the same directory as FirefoxPortable.exe, you would use LocalHomepage=homepage.html If it was in a subdirectory called homepage, you would enter LocalHomepage=homepage/homepage.html.

The WaitForFirefox entry allows you to set the launcher to remain active until Firefox has closed. This is useful if you wish to have another process wait until Firefox Portable has closed. The launcher will automatically wait for Firefox to close in cases where it needs to clean up after firefox.exe (for instance, to clean up %APPDATA%\Mozilla\Firefox when there is no locally-installed Firefox).

The DisableSplashScreen entry allows you to run the Firefox Portable Launcher without the splash screen showing up. The default is false.

The AllowMultipleInstances entry will allow Firefox Portable to run alongside your regular local copy of Firefox if you set it to true (lowercase). The default is false.

The DisableIntelligentStart entry allows you to to have Firefox Portable run its chrome and component registry fixes on every start. Normally, it tracks when you’ve moved to a new path (switching PCs for instance) and only processes the chrome and component registry when you do. By skipping it when the path is the same, Firefox Portable starts up faster. But, if you copy a profile into Firefox Portable between sessions (it handles a copy in on first run automatically), it won’t know to process these. This usually happens if you copy a profile into Firefox Portable from your local PC on a regular basis with a sync utility that doesn’t work with Firefox Portable (like Portable Apps Sync does). Setting this to true causes Firefox Portable to process each on every start.

The SkipCompregFix entry allows you to set Firefox Portable not to adjust the component registry (compreg.dat) for certain extension compatibility on launch. It is useful if you are only using Firefox Portable on computers you control and are able to have the drive letter set the same each time or if you are not using extensions which make use of the component registry (like Forecast Fox or the Mozilla Calendar) as Firefox Portable will launch more quickly. Set it to true (lowercase) to skip chrome.rdf processing. The default is false.

The RunLocally entry allows you to set Firefox Portable to copy your profile, plugins and Firefox binaries to the local machine’s temp directory. This can be useful for instances where you’d like to run Firefox Portable from a CD (aka Firefox Portable Live) or when you’re working on a machine that may have spyware or viruses and you’d like to keep your device set to read-only mode. The only caveat is, of course, that any changes you make that session (cookies, bookmarks, etc) aren’t saved back to your device. When done running, the local temp directories used by Firefox Portable are removed. RunLocally does not currently work with AllowMultipleInstances as it cannot track which version of Firefox is running. RunLocally will only use the 32-bit version of Firefox. Note that this option is not well maintained and may or may not work with each new release.

The AlwaysUse32Bit entry allows you to set Firefox Portable to use the 32-bit version of Firefox even when run on a 64-bit machine. This can be useful when used with a legacy plugin which is only available as a 32-bit plugin as well as when testing extensions and web apps.

This launcher contains suggestions from multiple sources. It began as a batch file launcher written by myself (John T. Haller) and posted to the thread about running Firefox from a USB key. tracon later released a launcher called fflaunch which I enhanced and re-released as Firefox Portable. mai9 later improved on fflaunch’s techniques and released it as Free The Fox. Multiple suggestions back and forth from mai9, myself and others lead to the launcher we have today. This most recent version adds my methods for allowing the code to be run from anywhere on first launch (as opposed to a specific directory), pass in commandline options, run without an ini file, allow the use of profiles from local installations, intelligent startup (the launcher determines whether paths have changed) and more.

INCOMPATIBLE EXTENSIONS – Certain extensions use additional local files or prefs.js in a non-standard way to store information, neither of which are handled by the Firefox Portable launcher when moving between machines.

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