I hope the extension can save the settings when it is deactivated. The current situation is that when the extension is deactivated by mistake and then activated, the new category settings in the container tab and the pinned tabs in the container tab will disappear, and the URL of the pinned tabs in the container will be lost without bookmarking.

This addon is really interesting and could probably be considered as a native feature in the future.
Nevertheless, potential users have to be aware that there are some known incompatibility issues at this time, such as the recurring login request when using Pocket (that can be solved by opening the submenu “Firefox Multi-Account Containers” and unchecking the submenu item “Always open in this container”).

Absolutely essential if you want to be more organised and/or more secure.

Serviceable, but could use enhanced features to help manage and prevent unwanted cookie-cross pollination into containers. An automatic default container would be nice for any website not in the whitelist.

EDIT: Adding an extra star to this as I realized toggling "limit to designated sites" for each container forces non-whitelisted sites into the default container, preventing unwanted sites from contaminating my custom ones.

EDIT 2: Container logic seems to be confused by URLs crafted to redirect. Doing things like checking my eBay watch list or seeing my previous orders on Ali Express force containers into an infinite authentication loop whereby I have to disable designated site limiting in order for it to work.

EDIT 3: June 14, 2022. This extension is dead now that Mozilla has enabled site partitioning by default in Firefox 101. Great while it lasted but it was klugy with third party cookies and single sign-on, etc. I mean, it'll still be useful to allow multiple sign-ons to the same site, but that's about it.

This is a great app and works very nicely with how various sites redirect you to their sub domains etc. The only thing I'd like added is
(1) being able to delete cookies and cache for a container group
(2) being able to assign different containers not only for different sub-domains, but different URI's

Absolutely necessary extension thanks! The only thing I wish would be to have entire windows automatically opening new tabs in the container of the other tabs of the window

Having separate cookies for each container is an absolute godsend!
The thing I really miss is, that you aren't able to set containers in bookmarks, that's why I deducted a star.

On YouTube, I have a container for each of my channels, so I don't have to switch accounts constantly, and each container is saved as a separate bookmark, so I can access that channel easily.

For the time being I installed a separate extension to solve this, but imho, this should definitely be solved in this extension, since this is a very basic/common request I would imagine.
https://addons.mozilla.org/en-US/firefox/addon/container_bookmarks/

Cool app. The only problem I have is duplication of containers on firefox updates. Not every update though.

It will open links to other websites into the same container if clicked on. It would be nice to have an option to disable this

This add-on is pretty great but there are time when it completely removes all my data and I have to basically re-start and re-setup all my containers and say which sites open up where for no reason.
Just happened tonight where my three pinned tabs were all of sudden closed (about 20 seconds after just freshly opening the browser) and my custom containers don't exist anymore.
Could be my own issue where I use Firefox Nightly during the day and sync with Firefox Beta in the evenings so the sync-ing process messes things up but I don't know.
Makes me sad.

would be nicer if you had 2 more options:

1) option to enable/disable "Sort Tabs by Container" within settings with a checkbox or move it somewhere else, where you can't click it by accident. It's more than annoying if around 600 tabs get rearranged when you had them in a specific order …

2) an option to force the current container to inherit and thus override the settings for target tabs during this session only. Use case: online shops have their own container, banks have their own container, thus you can't really pay in an online shop as it switches to bank container and thus loses all important cookies and payment information. Add a tick next to url bar for override during this session and bank and all subsequent redirects would thus get the online shop container but ONLY during this session.

Very good extension for when you have multiple Microsoft accounts. One problem: everytime I sync my containers on a new device it adds the default containers, I have to remove them one at a time.
Ideally, it would be nice to delete the defaults when I sync; at least it would be nice to have the possibility to delete multiple containers at once.

Missing export/import capacity.