If you need different profiles (like having different firefoxes installed, each with their own addons, themes, tabs, bookmarks, etc) you can use the built-in Pr

If you need different profiles (like having different firefoxes installed, each with their own addons, themes, tabs, bookmarks, etc) you can use the built-in Profile manager [0]. I personally have a secondary profile for testing, with some test addons and different bookmarks. If you only need different sessions (different cookies) you can use the official Multi-Account add-on [1]. I personally use it to be logged in simultaneously in two different accounts on sites where this is not possible (like GitHub). [0] : https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles https://support.mozilla.org/en-US/kb/profile-manager-create-... [1] : https://addons.mozilla.org/en-US/firefox/addon/multi-account-containers/ https://addons.mozilla.org/en-US/firefox/addon/multi-account...