There is usually no need to create an .exe file to install an extension.<br /> If you would drop the file in the extensions folder where Firefox would find it or add it via the registry then you will still get the regular request asking to install the extension on a next Firefox start.<br /> So you can give the user a dialog asking to accept the license and if the user confirms then copy the .xpi file to a location where Firefox will find it on a next start.<br /> You need to rename the .xpi to the ID of the extension (GUID or email). *https://developer.mozilla.org/en/Installing_extensions *https://developer.mozilla.org/en/Adding_Extensions_using_the_Windows_Registry *https://developer.mozilla.org/En/Developer_Guide/Customizing_Firefox