Best extension for privacy ever!
It makes possible to have several identities/account on the same platform.
Also, you can containerize websites which try to connect everything you do.
I wish it was available for Android too, but I understand it would require special UI and need more computing resources.

[to all the people finding it useful but complaining of minor missing features and giving few stars: it's not nice!]

Essencial. Essa extensão auxilia muito na privacidade. Abrir cada tema num container é imprescindível para uma navegação efetivamente privativa. Recomendo.

神了，超好用

Very useful to use several accounts of the same service. Also, to reduce unsolicited tracking.

Still the best

I LOVE this extension. I work at job that has me doing a lot of stuff and being able to separate my work web life from my personal web life is AMAZING! I can be logged into two CMS systems and never have to log out because of containers. It's glorious.

The add-on works well in the background and just shows a decent notification to check the visited website is opened inside the specified container. Good idea - great implementation!

Great functionality, avoids the need for having two browsers open for personal stuff, work, banking, shopping etc. The only missing thing is easy hotkey press defined by the user or something like CMD/CTRL+SHIFT+1 to open a tab in the container defined first.

suggestions:
1- organizing the containers in folders and sub-folders structure: I don't use it as much because I manage many accounts, and it would be nice to have the option to create folders. For example: you would have a folder called "Others accounts" and in it there is two folders "Managed businesses" and "family." Inside "Managed businesses" folder you would have business1, business2 etc.

2- adding description to containers and viewing them when hovering over them

3- have more custom control on colors and icons of containers, let the community make icons which could be added within the add-on

4- domain specific containers, example FACEBOOK.com

5- having two check marks; ☑ Always open this website/URL (Facebook.com) with this container (My Facebook) ☑ Except when I am in a different container.

Meaning if you made a container for a family member Gmail, Facebook, or their Other accounts; For example your mother, father, or technologically illiterate girlfriend accounts then you would be able to protect your privacy on ANY site not just Facebook, and manage other people or your other accounts.


Edit:

6- when long pressed the search bar or the arrow key in the Address bar button you can search or navigate to a site with a specific container

This tool is really helpful, as it helps me use different accounts for different services, without having to login and logout of accounts

As part of my work, I am regularly logging in and out of the same site with different usernames. Because each container holds its cookies separately, I'm able to run multiple instances of the site, which cuts back on my login/logout time and drastically improves my efficiency.

Firefox user for life because of this add-on.

I think there are a couple of additional features that could be added going forward, like default container and switch to container. But so far its brilliant and I get alot of use out of it, between personal and work accounts

very nice extension: it allows to easily manage multiple accounts (I use this to separate my work and home stuff)

Excelente, permite separar cookies y almacenamiento manteniendo una experiencia unificada de navegador e historial.

oui

An awesome addon that makes it easy to isolate work tabs and personal tabs containers allowing you to login into the same site with a different Identity in each container. The ability to give default containers for a site is also super useful.
Areas that require improvement:
Make it easy to edit list of domains to default container associations

Very useful. I like the new features (always open, hide container, etc.)

Очень удобное расширение. Как разработчик, часто приходится тестировать сайты, и контейнеры позволяют не запутаться между тестовым/продакшн сервером, а также помогают хранить раздельные аккаунты на разных сервисах одновременно. Короче, очень удобно)