Firefox Multi-Account Containers: what they are and how to use them
Firefox Multi-Account Containers is Mozilla's official, free add-on that splits your browsing into color-coded container tabs. Each container keeps its own cookies and site storage, so you can be signed in to two accounts on the same site at once, keep work and personal browsing apart, and stop sites in one container from reading the logins and tracking cookies of another.
This guide explains what containers isolate and what they share, how to create containers and assign sites to them, how Firefox Sync and Mozilla VPN fit in, and when a separate Firefox profile is the better tool.
What Firefox Multi-Account Containers does
Firefox Multi-Account Containers gives each container tab its own storage jar, while the rest of Firefox stays shared. A site opened in the Work container cannot see the cookies it set in the Personal container, which makes the container act like a separate browser for logins and tracking, without the overhead of a second profile.
Mozilla describes the add-on as a way to "carve out a separate box for each of your online lives". Typical uses are:
- Signing in to a personal and a work account on the same service (Google, Microsoft 365, AWS, social networks) in side-by-side tabs.
- Keeping banking and shopping sites away from social networks and their tracking cookies.
- Testing a site as a logged-in and a logged-out user at the same time.
- Separating client projects, each with its own set of accounts.
Each container has a name, a color and an icon, and the color shows as a line on the tab, so you can see at a glance which identity a tab uses. The add-on is built by Mozilla, is listed as an official add-on on addons.mozilla.org, is open source under the Mozilla Public License 2.0 and states that it collects no data. It requests access to tabs, browsing history and data on all websites, which it needs to open sites in the right container.
What containers isolate and what they share
Containers separate site storage, not your whole browser. Mozilla's Containers project documentation lists what is split per container and what stays shared across all of them:
| Data | Separate per container? | Practical effect |
|---|---|---|
| Cookies | Yes | Separate logins and tracking cookies per container |
| localStorage and IndexedDB | Yes | Site settings and offline data do not cross containers |
| HTTP cache and image cache | Yes | Cached files cannot be used to link visits across containers |
| History and bookmarks | No | Every container writes to the same history and bookmark library |
| Saved passwords and form data | No (by design) | The password manager can fill logins in any container |
| Extensions | No | Installed add-ons run in all containers |
The shared password manager is deliberate: you can save both of your accounts for a site and pick the right one in each container. The shared history is the main privacy limit, because anyone with access to your Firefox profile still sees every site you visited, whichever container you used.
How to create and use containers
Multi-Account Containers adds a toolbar button that controls everything. After you install the add-on from addons.mozilla.org:
- Click the Containers icon in the toolbar (or open the Extensions button and select it there).
- Click Manage Containers, then New container.
- Enter a name, pick a color and an icon, and save. Good starting sets are Personal, Work, Banking and Shopping.
- To open a tab in a container, click the Containers icon and select the container, or right-click the new tab (+) button for the containers menu.
- To edit or delete a container, open Manage Containers, select it, and change its name, color or icon, or click Delete this container.
Containers can also be managed in Firefox Settings: open Tabs and browsing, then Manage settings in the Containers section, where Add New Container and the edit and remove icons live.
Links and bookmarks can open in a container too. Right-clicking a link offers container options, and after you enable Bookmarks Menus in the add-on's Preferences (menu, Extensions and Themes, Multi-Account Containers), a bookmark's context menu shows Open Bookmark in Container Tab.
Always open a site in a container
Site assignments are what make containers work without thinking about them. Once a site is assigned, Firefox opens it in that container every time, even when you type the address in a normal tab or click a link from another site.
- Open the site you want to assign.
- Click the Containers icon and choose Always open this site in..., then pick the container.
- To remove an assignment, open Manage Containers, select the container, click Manage site list and click the trash icon next to the site.
For stricter separation, enable Limit to designated sites on a container. Sites that are not on its list then open outside it, in No Container, so a Banking container never ends up holding a news site and its trackers.
If you want throwaway containers instead of permanent ones, the third-party Temporary Containers extension opens sites in new containers that are deleted automatically. Single-purpose add-ons such as Facebook Container do one fixed assignment for you.
Site isolation: keep a container for its own sites
Site isolation lets a container hold only the sites you assigned to it, the reverse of sending a site to a container. Mozilla added it in a major Multi-Account Containers release in July 2020, and it is the feature behind the Limit to designated sites checkbox.
To set it up, open the site in the container, click the Containers icon, select Manage Containers, pick the container and check Limit to designated sites, then reopen the site and enable the always open option for it. Isolation works well for search engines: limit a container to Google Search or Bing, and every result you click opens in a new tab outside that container. The same approach suits link-heavy sites such as Reddit, Facebook, Pinterest or Twitter.
Sync containers across devices
Multi-Account Containers can sync your containers between computers through your Mozilla account (formerly Firefox account). Sync arrived in version 6.2 in February 2020, and according to Mozilla's announcement, it carries over container names, colors, icons and site assignments to other machines signed in to the same account.
To use it, sign in to the same Mozilla account in Firefox on each computer, install the add-on on each one, and turn syncing on from the add-on's prompt or its Preferences page. Sync moves the container setup, not the data inside it: cookies and logins are not copied, so you sign in to your accounts once per device in each container.
Use Mozilla VPN per container
Multi-Account Containers can route individual containers through Mozilla VPN, each with its own server location. Your Shopping container can use a server in one country while your News container uses another, and the rest of Firefox keeps your normal connection.
The feature needs an active Mozilla VPN subscription, the current Mozilla VPN client installed and signed in, and the add-on. Per Mozilla's VPN container guide:
- Install and sign in to Mozilla VPN so the add-on can detect it. The VPN logo and a status indicator appear in the add-on panel.
- Click Manage Containers and select a container.
- Switch on the Mozilla VPN toggle in the container's editing panel and choose a location.
- Check that the container now shows the flag of the chosen country.
Mozilla notes that the integration does not work with Snap or Flatpak installs of Firefox on Linux.
Containers vs Total Cookie Protection and Firefox profiles
Containers, Total Cookie Protection and profiles solve different problems, and many people use all three.
- Total Cookie Protection is on by default in Firefox and gives every site its own cookie jar, so third parties cannot follow you from site to site. It does not let you hold two logins to the same site; containers do.
- Containers separate cookies and site storage per identity inside one profile, with shared history, bookmarks, passwords and extensions.
- Profiles separate everything: history, bookmarks, passwords, extensions and settings. They suit fully separate work and personal setups. See the guide to about:profiles and Firefox's new profile management menu.
Choose containers when you want several accounts in one window with one bookmark library, and profiles when work and personal data must never touch.
Where Multi-Account Containers came from
Multi-Account Containers started as a Firefox experiment before it became an add-on. Ghacks first previewed Container Tabs in June 2016, and Mozilla later offered the feature as a Container Tabs Test Pilot experiment, the program it used to learn which new Firefox features people liked and which they ignored.
When Mozilla published Multi-Account Containers as a standalone add-on in September 2017, it supported Firefox 51 and newer, shipped with four default containers and already offered the option to always open a site in a chosen container. Firefox itself also included a native containers implementation at the time, switched on with the about:config preference privacy.userContext.enabled.
FAQ
Is Firefox Multi-Account Containers free?
Yes. The add-on is free and open source from Mozilla. Only the optional Mozilla VPN integration needs a paid subscription.
Does Multi-Account Containers work on Firefox for Android?
Containers are a desktop Firefox feature. Container support for Android is an open user request on Mozilla Connect, and Mozilla has not announced a release.
Do containers work in Private Browsing?
No. Mozilla disables containers in Private Browsing windows and when Firefox is set to Never Remember History.
Related: the best Firefox add-ons, Cookie Quick Manager for site-specific cookies
I cannot get syncing containers to work, I am running firefox 80.0.1 on both computers, if I change the firefox account picture it changes on the other, I have a different set of containers on each computer. I have ticked sync everywhere I can find it.
Also it says I can use it on my mobile (firefox 80.1.3 )but I cannot see containers on that at all, if I go to addons I can only see recommended ones.
it is very inconvenient to assign new domains to a container.
Can’t a whole list of domains be integrated via user.js? Any other sollutions to this problem?
Rather surprised mozilla have not incorporated this feature into firefox itself.Months ahead this may be the intention.
Hi, Martin, you should make an article about Waterfox being sold to System1, that also bought StartPage search engine:
https://old.reddit.com/r/privacy/comments/f3gqoc/privacy_browser_waterfox_appears_to_be_sold_to/
Will this add-on be eventually built in for Firefox or will it be always an add-on?
o/t https://old.reddit.com/r/privacy/comments/f3gqoc/privacy_browser_waterfox_appears_to_be_sold_to/
Containers are really useful. With one browser you can have multiple separate “browsers” open for different tasks.
Containers with transitions is really useful extension.
It just needs one more functionality- Limiting a container only to the assigned websites.
A must have container for privacy conscious people.
First it was separate processes for tabs, and now CONTAINERS!!!
Soon 16GB of RAM might be insufficient to load the Askwoody Lounge with threaded comments…
Thumbs Up, Yuliya.
Your name says it all. You don’t deserve to use the latest Firefox. Do yourself a favor. Create a time machine, travel back to the past and enjoy.
Don’t use them if you don’t like them. It’s so simple. Like I said to him too, grow up, the whole world doesn’t revolve around your how to’s
I don’t think you have any idea what Containers are or how they work.
Geez, can you be more ignorant?
God almighty, do you even understand how containers work?
Not sure if you used containers regularly but I’ve been using them for long time and absolutely love it. Sync is the best thing ever.
You cannot import export containers. To understand why you need to use addons such as NoScript, cookie blocker, adblockers etc. these addons works with containers. So if in 1 containers you block a cookie using addon, in another container you can have that cookie unblocked. You can assign different websites to automatically open in different containers automatically.
I am a programmer and I created an addon for Import/Export containers with which you can take containers from on PC to another (just copy your containers.js file to the other PC) but then all your website based settings and addon settings will disappear.
I love Containers! They are fantastic at keeping things silo’d. Very flag to see new features, it tells me they aren’t going to abandon Containers any time soon. Woot!
import export is a hassle when everything else syncs without issue.
Sync? What is wrong with export/import data? Does moz://a want even the colours you assign to a container off their users?
Lol, enjoy your posts Yuliya. Don’t stop. Its funny seeing a certain bunch get triggered because theyre so invested or whatever (like why does it matter?). BUT, often, you and a few others give a good reason to pause and say “why do i need this?”, and why are resources prioritised in ways which encourage account usage? A neccessary breath in the winds of marketing.
Yuliya, you’re just a fanatic at this point. A fanatic with a mission, like all fanatics. Please stop. Mozilla is crap to you, we got it already.
Because if you’re using multiple devices, it takes much longer to export/import each one. With Sync you just change one device, and all the rest are instantly updated to match. I’ve used Sync for years. So easy to use. Do something on one of my PCs, travel somewhere, and still have all my stuff even on mobile. Love it.
I have multiple PCs and laptops, they all have access to the same NAS. I can grab everything from there with any device. Mobile phones too.
Yuliya grow up, the whole world doesn’t revolve around your how to’s. Nobody is going to buy NAS for syncing their browser in multiple devices and the most important they don’t care to learn how to set up NAS.
Yes, well how many people are going to set up a NAS to sync their browsers.
Doesn’t everyone has their own NAS? – Yuliya
There’s nothing wrong with export/import but good luck trying to explain that setup to the vast majority of internet users. It’s also in the article that this was a “long request feature” so there’s clearly some interest for it.
Even if you know your way around it, most people welcome this feature anyway because there’s no need to trouble with every single aspect of your browser. I for one like and prefer to have this kind of stuff done automatically for me.
Your ignorance matches your need to troll.
Just because this doesn’t suit you, doesn’t mean that others (like myself) won’t find it very useful.
Do you really have to make your stupid comments on every article? PLEASE, do us all a favour and stop commenting on ghacks!
A LARGE portion of users of EVERY browser, not only Firefox, WANT to sync their data. This is a great feature for everyone who want this. And, with every optional feature, you DON’T HAVE to sync the data.
Your comments are embarrassing, Yuliya.
Yuliya always provides a different point of view with solid reference material to back each claim, and I for one, enjoy reading someone who is outspoken, critical and intelligent.
As a privacy conscious internet user, I use an enhanced and modified version of Firefox web-browser on a daily basis, but as much as I think Firefox is a great piece of software in comparison to the competition, Yuliya’s criticisms are valid and, most importantly stimulate discussion.
lol. The portion of users using sync fetaure of any browser is insignificant; less than 1%, as Opera released the stats a while ago.
Idk, I don’t feel embarrassed. Do you?
I use sync and I really like it, because it’s reliable. The downside is not every browser has proper sync. So far only Chrome, Opera and Firefox do it for me, the rest are just horrendous in terms of syncing.
Tried to migrate to Vivaldi.. doesn’t sync passwords.
Tried to migrate to some Chromium fork – they have Google accounts disabled.
Brave’s sync is dumb in the first place and it also doesn’t work.