There's an add on that lets you create custom containers, a container acts as it's own session in a way, content, cache, cookies etc are all localised to one container
For example, you open youtube in one then open gmail in another container, neither one will know you're logged into the other
A little while back Mozilla put out a post ushering addon developers to prep their addons but I haven't heard anything else since, I don't wanna update to early and loose everything I already got
There's an add on that lets you create custom containers, a container acts as it's own session in a way, content, cache, cookies etc are all localised to one container
For example, you open youtube in one then open gmail in another container, neither one will know you're logged into the other