I have multiple Firefox profiles for different purposes. Often, I have at least two instances of Firefox running at the same time. When opening links from other applications, I would like to be able control in which profile the link should be opened. If there's already an instance with that profile open, the link would be opened there, otherwise a new Firefox instance with that profile would be created and the link opened in it. This is what I would like to achieve ideally. Currently I only understand two options, both of which in the end do not work for me well: 1) I have one Firefox instance without the -no-remote option open. Then any link from another application will be opened in this instance 2) All Firefox instances were started with -no-remote. This is actually very close to the desired behavior. Now, after clicking the link in an application, the Firefox profile manager pops up and I can select the profile I want the link to be opened in. However, currently only profiles that don't already have an instance running can be selected. If there's already an instance with that profile, I get the following error: Firefox cannot use the profile "my_profile" because it is in use. If I could just "trick" the profile manager not to try to open a new instance when it already exists, but instead just open the link in this existing instance, I would have exactly the functionality that I want. Any ideas how to go about this? There have been questions addressing the similar problems before, but without any definitive answers: https://support.mozilla.org/en-US/questions/999493?page=1 Any input is appreciated!