Firefox has a built-in feature that Chrome doesn't: Multi-Account Containers. Here's what they are, why they matter, and how to actually use them.
What Are Containers?
A container is a separate cookie jar. Tabs inside a container share cookies with each other, but not with tabs outside it.
Practically: you can be logged into your personal Gmail in one container and your work Gmail in another — in the same Firefox window, at the same time. No second browser, no private window, no profile switching.
This is different from Incognito/Private mode, which discards all cookies when the window closes. Containers persist until you delete them.
The Technical Part (Brief)
Firefox implements containers using "contextual identities" — each container has its own:
- Cookie store
- localStorage
- IndexedDB
- Cache (in some configurations)
Network requests still go through the same IP. Containers aren't VPNs or privacy tools against server-side tracking. They isolate sites from each other, not from the sites themselves.
Setting Up Containers
Firefox ships with containers disabled by default. Enable them:
- Install Firefox Multi-Account Containers (official Mozilla extension)
- The toolbar gets a container icon
- Right-click any link → Open in [Container]
Or go to about:preferences#containers for a simpler toggle if you just want the basic 4 built-in containers (Personal, Work, Banking, Shopping).
The Most Useful Configurations
Multiple Accounts on the Same Site
Open two tabs with the same site in different containers — you'll be logged into different accounts in each.
Use cases:
- Two Google accounts (work + personal)
- Two Twitter/X accounts
- Staging vs production on the same app
Site Isolation for Security
Assign specific sites to containers permanently via the extension. Example: always open your bank in "Banking" container. This means bank cookies are never shared with other sites, even by accident.
Developer Setup
Some developers use containers to simulate different user states:
- "Logged in as user" container
- "Logged out" container
- "Admin" container
Without containers, testing multiple states requires multiple browser profiles or constantly clearing cookies.
Work/Personal Split
Assign work-related sites to a Work container. Every personal site stays out of it. Useful for:
- Preventing cross-contamination of tracking data
- Keeping work login sessions separate
- Single-user laptop shared for both work and personal use
Keyboard Shortcut Workflow
With the extension installed:
- Click the container toolbar icon → select container → opens new tab in that container
- Right-click a link → "Open Link in New [Container] Tab"
- Long-press the new tab (+) button to pick a container
Temporary Containers
The Temporary Containers extension takes this further: every new tab gets its own unique container by default, discarded when the tab closes. This gives you a fresh cookie state for every site, automatically.
This is more aggressive isolation — each site you visit can't track you via cookies from other tabs (since each tab has a fresh cookie store). It changes how browsing feels significantly, but some people use it as a default.
What Containers Don't Do
- They don't hide your IP from websites
- They don't prevent browser fingerprinting
- They don't prevent JavaScript tracking pixels or canvas fingerprinting
- Tabs in the same container can still set/read cookies from each other
For fingerprint resistance, Firefox's Strict Tracking Protection and the uBlock Origin extension are more relevant tools.
Containers in Firefox for Android
As of Firefox for Android v120+, containers are available (with some limitations). The container functionality works but the UI is simpler than desktop. You can enable it the same way through the Multi-Account Containers extension.
Tab Management Across Containers
One limitation of containers: if you have lots of tabs across multiple containers, the built-in tab bar doesn't give you a great way to organize them visually.
Tab Manager & Session Saver works alongside containers — you can see and navigate all your tabs by site, and save named session snapshots. The container assignment is preserved when you save/restore sessions.
Multi-Account Containers is one of those Firefox features that once you start using, you can't imagine browsing without. The ability to be logged into multiple accounts for the same service simultaneously is something Chrome users have to use separate browser profiles or work-arounds for.
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