An incredible and very unique add-on that lets you have multiple isolated tabs/sessions at once in the same browser. Its best feature is the "restrict to site" so if let's say I put Google search inside a container and restricted it, everytime I wanna search something in the search bar it automatically opens up Google search in that container, isolated from every other tab and from my session, it opens Google search in an contained tab, Firefox within Firefox, Fireception. This is an essential add-on to have for anyone who cares about enhancing privacy. It's absolutely brilliant and you can't find it in any other browser.