Works well for my use (on a single machine). I haven't used the sync-option! Other reviews report it is buggy...

Needed to have multiple Web Outlook email accounts open simultaneously. Worked great. If pinned the accounts came back up without logging in again if Firefox exited and restarted. Would be absolutely perfect for me if the accounts came back up after a Restart.

De ideale manier om met meerdere accounts en een domein te werken zonder van profiel te hoeven wisselen.

This extension is 100% what's keeping me on firefox

Works well for seperating my tracked internet history, without needing to setup a second Firefox Profile & Mozilla Account. This in addition to the Facebook, Google & Twitter Containers help keep those 3 from tying everywhere I go on the 'net to my accounts.

this is the god extension for me. my life saver please continue. dont stop ever. i love you firefox

This is very powerful tool for productivity. I shifted from Chrome to Firefox a week ago.

Must have extension for every developer.

It is a must have extension. I primary use it during development where I need different states of cookies and logins.

The only thing I'm missing is to be able to open a URL in a specific container e.g. by specifying a protocol prefix in a href (or whatever data-x-target="{container name}").
I can not assign a full domain as I need to view the same domain in different configurations, but I'd like to access them by just clicking on my "bookmark" link - My site (Beta-2), My site (Alpha).. etc...