Super helpful to manage multiple accounts across the same website, MS, etc so there's no overlap between the different tabs

very informative

Very good add-on, 6 points from 5

Absolut unverzichtbares Tool und Alleinstellungsmerkmal von Firefox.

Truly helpful add-on. Love it.

I couldn't imagine using a browser day to day anymore without this feature.

To @daze who asked about changing stuff once it's set to 'always open'. Click on the Add-on int he toolbar, go to 'Manage Containers' > choose the container which was assigned and then select 'Manage site list'. You can then remove sites from opening. It would be nice if it could be disable temporarily.

Whoever came up with this is a genius!