Functionality is ok. Wildcard domains is needed. Like *.tumblr.com.

Also, using "manage containers" to order the list of containers does not seem to get picked up afterwards by any other menus. Trying to re-open a tab in a different container? The list you get is out of order. Only the list in "manage containers" seems to keep the order you gave.

Adding an already opened page to open in a specific container in future should be an option. As of now it only shows option to add to default continer.

Absolutely great add-on!
Should be a built-in (or added by default) feature.
It's my No#1 tool for keeping services separated from each other, e.g. Facebook separately contained, News websites with their tracking cookies separately contained, other user accounts/profiles in various other websites and/or services w/o any association between them all.
It's like having multiple, persistent "Private Browsing / Anonymous" tabs with the ability to define a persistent default container for every website (e.g. clicking a Facebook link will always open up in a pre-defined Facebook container tab).
I love it and use it all the time!

Very good idea, needs more work, but nevertheless extremely useful in 2019s internet

really needs to be a built in feature, love it!