(X) Free and Open Source
(X) Trustworthy company
(X) Modular

I'm a big fan of this way of implementing advanced features - not adding bloat to the main browser, but enabling these features to all. Also is a modular approach for the casual hackers to make their own extensions based off of it.

Very useful to have multiple sessions open, I did not have any problem so far with this addon.
I recomend!!

Very useful

Very easy to use and user-friendly.

If Firefox has one "killer feature" this is it. It completely transforms the way a browser works, essentially creating sandboxed groups of pages that can only see others in the container and nothing else. It makes using the same site with multiple credentials painless and overall increases the security and privacy of browsing exponentially. If I had one gripe it's that the UI is a little clunky and it could really use some love. Otherwise, a huge thanks to the team behind this. You should be marketing this way more than you do.

love this extension for keeping my privacy private across the internet. i had no idea until i discovered this extension that sites such as facebook tracked u all across the internet. thanx firefox! ure still #1!

This nearly replaces Firefox Profiles for me and is so much easier to manage. The automatic rules for always opening certain sites in a container is great and makes logging into multiple accounts for a service in one browser possible without Guest profile windows or private browsing mode.

This has been great for separating certain categories in a sandbox-like manner so that even if I leave cookies etc from say Facebook (created a container category for Facebook) and I go to my Banking site (in the category of Banking) there is no visibility between the two, so Facebook doesn't get to datamine anything about my banking (also a security precaution, security in layers like an onion), etc. Also this is super simple to use and allows me to organize my tabs more efficiently (I use a lot of tabs).

Amazing and helpful. Makes working with multiple Microsoft accounts for different things so much easier. Also works with Facebook Container extension. Makes everything a bit more private with how it contains cookies.

Productivity savior. Makes my life so much easier as a consultant with multiple client profiles.

this extension is perfect!! i used to use multiple browsers with dif accounts on each, but now i can use just one browser and easily jump around between my numerous accounts. works as advertised.