Firefox Containers Preview

I’ve been using Firefox Containers for years through Mozilla’s Multi-Account Containers extension.[1] Now that container management is available directly in Firefox, I’d prefer to use the native implementation if possible.

Mozilla notes that the extension still adds some functionality:

> “Installing the Multi-Account Containers extension developed by Mozilla provides a few benefits on top of the native container functionality like site-specific container assignments, syncing across devices, and integration with Mozilla VPN or your own proxy.”[2]

I don’t currently need any of those additional features, so the native version would probably be enough for me. What I haven’t been able to figure out is how to switch without losing my existing setup. Are the containers created by the extension already shared with Firefox’s native container manager, or is there some migration process? Can I safely uninstall the extension and keep my existing containers, names, colors, icons, cookies, and active sessions?

[1] https://addons.mozilla.org/en-US/firefox/addon/multi-account...

[2] https://support.mozilla.org/en-US/kb/how-use-firefox-contain...

Good that they are integrating that into the main browser.

For me the big use case is having different Google accounts active in one window. Work and private. And when I was doing freelance projects, I sometimes had 3 or 4 different Google accounts active. Plus assorted stuff tied to those accounts. Using different colors for each makes it easy to tell apart the tabs.

Another use case is if you are testing the same app for different customers with different credentials. I do this a lot and I have dedicated containers for each customer so I can easily switch with out having to log out and in a lot.

And of course some companies that can't be trusted with cookies, like Facebook, get isolated. I open that container less and less these days. But I still check every few months. I also keep my bank's website in its own container just on principle.

Firefox's Multi-Account Containers changed the game for me back in 2018 or 2019, and is what got me to switch back to Firefox for 95% of my personal browser use. The "Always open {{domain}} in this container" and the ability to open a specific container with a keyboard shortcut seem like small things, but I can't imagine life without them anymore.

I never understood why it was set off to the side in an (official, first-party) extension, because I was always afraid they would one day stop supporting it. Now when I explain to people why I prefer Firefox, I don't have to explain "There's this extension, don't worry it's official, that allows me to..." I can just say "It has containers built-in. They're great. Try them."

I use profiles for this, I wonder what the tradeoffs are between the two approaches. I've actually been thinking about building some tools to make it easier to create and manage profiles on the fly. For me I really think profiles are better since the boundaries are harder - there's no worry about accidentally hitting the "log in with Google" button and clearly identifying myself to a site or similar, because I read the news in a separate profile from my Google account. And it would be nice if those sort of guardrails were very intuitive and easy to set up by default. But I feel like containers may be too squishy.

This is great, and the direction Firefox should focus on: creating user-first features that other browsers won't and extension authors can't.

I only wish it was more automated. Every site should automatically get its own container.

How much of the anti-tracking value is defeated by non-cookie browser fingerprinting?

Oddly enough I thought Firefox had that a few years ago. I forget what I used - maybe a Mozilla extension? - but it even colour-coded tabs.

Am I wrong? Was it unofficial? A hack?

This is not new, and it's weird that this blog post doesn't acknowledge that.

A a snapshot from 2017 [0] of their docs show the UI for this very feature. A snapshot from 2023 of their knowledge base [1] says that "Firefox Containers is a basic built-in feature".

I just created a new profile in Firefox 140 ESR, started it in safe mode (which disables extensions), enabled "privacy.userContext.enabled" in about:config - and there you go, native containers accessible from File -> New Container Tab.

I'm not talking about the Multi-Account Containers extension. There are no extensions installed or enabled. It comes with Firefox 140 ESR, without extensions.

The Containers feature is already a "native, first-party feature" in older versions of Firefox. Firefox already has a "first-party version of containers". They have already brought it "directly into the heart of Firefox for all to benefit".

So what are they talking about in this blog post? Are they simply flipping the config setting to true by default? Are they replacing the existing "Containers" feature with a new feature which is also called "Containers"? Are they rebranding the Multi-Account Containers extension as "Containers" and making it built-in (seemingly not, since apparently "Not all of the features of the add-on are available in the first-party version of containers").

[0] https://web.archive.org/web/20170821073747/https://developer...

[1] https://web.archive.org/web/20230307151023/https://support.m...

Multi-Account Containers paired with Container Proxy allows for some really cool setups. I especially like the options to use socks proxies. Hope they will add proper proxy support later.

My guess as to what's new here is... nothing.

I'm thinking they will change the containers preference to default to on, and if the extension enabled the preference before maybe that's being removed. Otherwise the containers functionality in Firefox or the extensions in the extensions remain exactly as they were before.

So you still need the extension as it has the critical functionality of Ctrl-Shift-1 to open a new tab of the first container type.

I am a big user of the multi-account containers extension. It is nice to keep banking in one container, Amazon in its own container, social media in its own, and so on.

Syncing across device and always reopening a certain site/domain inside a specific container are must-have features, so I think I'll keep using the extension until they are available natively.

But Firefox also has browser profiles now (something I wanted for so long I moved back to chrome to get it), so what’s the purpose of first-party containers now? Don’t browser profiles provide a more robust, very visible delineation between different accounts/user profiles?

I'm glad that Firefox is catching up, but they still have a lot of catching up to do compared to Arc/Zen. You got people out there like xe-darc innovating on putting Docker containers in your browser, and Firefox is just getting preview support for built in profiles.

I hope they improve the UI, it has been difficult to use. Several menus with different random functionality that don’t have the options I’m looking for. Many times I have to hunt through the extension preferences to do simple things.

Also the “temporary container” extension is quite useful and closer to what I need in the first place.

Does Chrome have this yet? It's basically the single feature I use Firefox for. And no, container tabs & incognito mode don't count.

Amazing news. Wonder if this will be synced on multiple machines through Mozilla Connect, since that wasn't the case with the Mozilla’s Multi-Account Containers extension before.

I hope it is, since it was a major pain point before.

Are they shipping it on Android, too?

tree style tabs and container-locked windows. that will make firefox perfect.

I'm a little confused here, I've been using the containers feature already for years now on Firefox. And I have no add-on installed for it, it just works.

So what is it that they're adding?

I'm curious about Mozilla's seeming shift in strategy (possibly it was awhile ago and I overlooked it):

For a long time, with relatively limited (compared to Google and Apple) development resources, they focused on minimizing upkeep and technical debt. They added and maintained features appealing to the vast majority, the non-technical users, and left the rest to extensions.

Now I'm seeing geek and power user favorites like a built-in color picker, PDF editing features, and now multi-account containers moved into the browser. What changed? Are they focusing on different audience? Do they have new resources so that they can afford maintaining all these additional, more niche features?

I would love to see a better UI for

  - Forcing container usage/default window popup for assigning sites to containers
  - Viewing a list of websites assigned per container

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