Doesn't work at all. "View preferences and synced containers" shows no preferences (nothing), "Backup" shows a never ending spinner that tell us that it can't finish the saving action.

Only syncs names of the container, not their patterns or settings

Doesn't work. Backup and Restore buttons don't make sense, doubtful functionality. Everything gets sync'ed except containers.

Doesn't work anymore :-(, but it was a nice idea

Just doesn't work on current firefox

After some initial issues with this add on (couldn't figure out why), it finally worked w/o any problems.
However, out of a sudden, it stopped working recently without any hints so far. while my custom named containers are still present on one (Window) PC, the names and containers in general reverted back to the default ones, on the other PC.

Syncing, e.g. bookmarks, is still working btw. between those PCs!

Using th latest available Container Sync version.

I could get my containers back, restoring the file containers.json, however, not those settings which bookmark opens in which container.

** Does anybody know the location where the container add on remembers the appropriate container for bookmarks? **
-> Found it! Information is stored within the users profiles folder, subfolder .\browser-extension-data\@testpilot-containers file storage.js

back-up and restore button show "done" but nothing happens.
"view synced containers" doesn't do anything

Tl;dr: do not use this add-on (yet). It lacks any feedback for user actions, has no sync for tabs inside containers, and can simply remove all your containers with whatever is inside without any warning.

A note to developer. As you mentioned in readme on GitHub:

>What does the reset button in the popup do?
>It will remove all containers from your device and also from the sync storage

Why is that so? By common sense, it should remove containers from local device only, but keep those in sync storage for further restoring. Moreover, there is no warning for such dangerous action, nor feedback afterwards. Such operations must prompt user for confirmation before simply deleting everything.

P. S. To any Windows users who have suffered complete removal of containers and tabs within because of this add-on – there is a chance to recover them by restoring previous version of containers.json. First you need to locate your profile folder: go to Firefox Help → Troubleshooting Information → Profile Folder → Open Folder. Then you need to find containers.json, right click on it and choose Properties → Previous Versions. If you are lucky, there will be saved version of your previous containers, and you can restore it by clicking respective button. Worked for me on Windows 7.