Do not use Temporary Containers.

This extension to Multi-Account Containers looks great at first -- its Automatic mode spins up a new container each time you open a new tab, then switches that tab to an existing container, should one be associated with the TLD you visit.

The problem is that Temporary Containers does not delete these temporary containers. They accumulate in the MAC containers list. There is no way to mass delete them, nor set them to auto-delete when the tab is closed.

These WILL sync to your Firefox account and reappear on every machine. Over 3000 temp container made MAC unusably laggy. This was so destructive of my MAC experience that I uninstalled both extensions. Unfortunately, to my knowledge, there is no way to reset the data MAC syncs to Firefox Account.

Temporary Containers has an option "Delete no longer needed Temporary Containers" which defaults to 15 minutes, but can also be set to immediate.

Are you setting this option to something else?

Temporary Containers works really well for me. I have per domain isolation, which only breaks very very few sites (Gmail and Outlook 365). For those I have regular persistent containers. Alternatively, I can always open a new private window where I don't have this plugin active.

uBlock Origin + Temporary Containers + ClearURLs are a great setup for privacy and security. Actually, I don't need much else aside from a VPN and a few settings in my user.js.

The only thing I miss is Vimperator. Modern alternatives are full of glitches because of inherent limitations in the WebExtensions API.

It's a long-standing bug that also affects me. It's quite annoying since it's easy to irreversibly hose up your sync account by going over the remote storage quota. Maybe you don't have a Firefox account and/or sync setup?

There are related issues opened for Temporary Containers, MAC and Firefox and at least from the public discussions not much is happening about it.

I use Temporary containers heavily and the MAC sync is also enabled but I never see anything like this. Sometimes 1-2 container it remains but I can delete it manually. Maybe I'm lucky with this.

Here is the issue if you are interested. It's still not closed: https://github.com/stoically/temporary-containers/issues/371

> The only thing I miss is Vimperator. Modern alternatives are full of glitches because of inherent limitations in the WebExtensions API.

Didn't use Vimperator, but I found Tridactyl to be pretty good, especially their hinting mode.

"Delete no longer needed temporary containers 15 minutes after the last tab in it closes" is a default setting. This is not an issue I've experienced in the 3+ months I've been using this extension.

Are you sure you didn't accidentally change it?

I don't know what, but something causes it to leak. I've been using it for about a year and several of the low numbered containers have accumulated duplicates:

Edit: Apparently HN strips box drawing characters. Imagine the output of `sparklines 6 15 7 5 2 1 1 4 3 1 1 1 1 1 1 1`.

I can confirm what others are saying, using temporary containers with the default settings left me with hundreds of containers to clean up.

I don't remember what the default settings are, but I do remember changing a fair number of them (and they are numerous). Definitely not the most friendly tool to casual use. But when fully configured, it is my second favorite addon (behind uMatrix).

I had the same issue and this was always enabled

I have the same problem (which supposedly does not happen to all users of that extension). I fix it by running this script once a month (it deletes the temporary containers from the containers.json file):

    import json

    with open('containers.json.bac') as f:
        s = f.read()
        j = json.loads(s)
        ids = [i for i in j['identities'] if not i['name'].startswith('tmp')]
        print(len(j['identities']), len(ids))
        j['identities'] = ids
        with open('containers.json', 'w') as wf:
            wf.write(json.dumps(j))

You can reset your sync data for any extension in Firefox.

Just go to about:debugging, click on "This Firefox", locate the extension and click the "Inspect" button. In the case of MAC this should lead you to about:devtools-toolbox?type=extension&id=%40testpilot-containers

In the devtools that open you need to go to the Console tab and run this command:

  await browser.storage.sync.clear()

If you want to see the data before you delete it, you can show it with this command:

  await browser.storage.sync.get()

The only passable workaround is to enable "Reuse available numbers" for container numbering setting.

At least this way yo won't end up with unusable FF because of the thousands of undeletable temporary containers.

Huh, I have not experienced this issue, but there seem to be mixed reports in these comments. The numbers continue to count up (this is also configurable), but the containers are actually deleted.

I had the same issue and uninstalled both.

I used to delete manually each container when this happened, through about:preferences container manager, but now there is no more this in Preferences and to remove containers through the Multi-Container extension isn't the best thing.

Tried do that by editing some files too but the hundreds os containers keep reappearing after few days, or on new installations.

Worth pointing out that while they're probably safe (and do in fact use the same container APIs to separate out the domains), these are all from third-party developers. Where as the Facebook container is from Mozilla directly.

Multi-account containers IS made by Mozilla, actually

You can make all of these yourself as long as you've got the Temporary Containers add-on installed. I don't see the benefit of installing four addons for this purpose, as the security risk of third-party addon vendors surely outweighs the convenience of a pre-configured container.

Has temporary containers gotten the feature to drop the container when leaving the target sites? That's the main difference for me.

If I'm in FB Messenger and click an external link I don't want that link to be opened in the FB container.

I think it's actually just a containers feature now: https://news.ycombinator.com/item?id=24850878

I use per-domain isolation, so I don't run into this issue.

However, I need 2 manual persistent containers for sites that are broken with per-domain isolation (Gmail and Outlook 365). Both visit many different domains after login. Within those containers, I need to be careful not to click on external links, but to open them in a new temporary container.

Is it possible to have each domain open in a persistent container? It looks like Temporary Containers uses a new one each time a site is visited. Containerise, on the other hand, seems to need to know about each domain in advance.

I use persistent containers based on domain. Works brilliantly.

With what addon?

I only use the official "Firefox Multi-Account Containers" (on this browser).

It gives me a menu with choices like "Reopen This Site in..." and "Always Open This Site in..." as well as options to open a new tab in any of the permanent containers or even open new ones.

Tip: if anyone gets confused by a page popping up, saying something like "You asked me to always open this site in, do you still want to " a typical explanation for me was I had set at site to open in a specific container but as part of login procedure it would access another domain for sso, trigger "Always Open This Site in..." for that domain and get confused.

Now that you know this you should probably be able to either avoid it completely by being specific about subdomains or something.

It is not a big thing, just a heads up so nobody gets confused.

The issue with this was using multiple Google identities. The Google Container Extension would want to open any other Google sites in the same container.

I wanted to keep the soccer club administrator, school website, etc. Google identities separate and distinct.

Perhaps things have changed and this isn't an issue anymore. What I did was create an identity (soccer, PTA) for each gmail account and set defaults for google.com, YouTube.com, etc.

Having [email protected] is really nice for being able to give someone else the password and let them take over the account when your term is done.