Firefox Multi-Account Containers are one of the browser's most powerful privacy features. Most users know the basics — here's what you can do with them beyond the defaults.
Quick Refresher
Multi-Account Containers isolate websites into separate "containers." Each container has its own cookies, localStorage, IndexedDB, and cache. A site in Container A can't see cookies from Container B.
Think of each container as a separate browser profile, but all within the same Firefox window.
Install from AMO: Multi-Account Containers
Use Cases You Might Not Have Tried
Isolating Work and Personal Google Accounts
Classic use case. Put your work Gmail in a "Work" container and personal Gmail in a "Personal" container. Both stay logged in simultaneously, no incognito windows needed.
Testing Logged-Out vs Logged-In State
Developers: open your site in a container where you're not logged in while staying logged in in the default context. No need for incognito mode or a second browser.
Isolating Social Media Trackers
Create a "Social" container that's only used for Facebook, Instagram, Twitter/X. Never open those sites outside the Social container. Their tracking pixels and cookies are confined to that container.
With Firefox's Enhanced Tracking Protection (Strict mode) + containers, social media sites can't build cross-site profiles from your browsing.
Amazon Isolation
Amazon places tracking pixels on many retail sites. Put Amazon in its own container so its cookies don't leak when you visit sites that use Amazon's ad network.
Separate Financial Container
Banking, credit cards, financial accounts — all in one container. These sites tend to be security-sensitive; isolating them reduces the attack surface if any other site is compromised.
Site Assignment
Right-click any tab → "Always Open This Site in ___ Container"
Once assigned, Firefox automatically opens that domain in the right container every time. You don't have to remember to switch.
You can also configure this via the extension popup: click the multi-account containers icon → "Manage Containers" → "Add" → assign URLs to containers.
Temporary Containers Extension
The official extension lets you create containers manually. Temporary Containers extends this with automatic isolation:
- Every new tab can open in a fresh temporary container
- Containers are deleted when all their tabs close
- Great for browsing untrusted sites with zero cross-site leak risk
Use with Multi-Account Containers for the best of both: permanent containers for known sites you want to stay logged into, temporary containers for one-off browsing.
Container-Specific Bookmarks
There's no native UI for this, but you can use the container: prefix in bookmark URLs (via about:config or the Container Tabs extension API) to open bookmarks in a specific container.
Alternatively: keep container-specific links in a pinned tab in each container.
Debugging with Containers
For web developers, containers are useful for:
Testing cookie isolation: Open the same URL in two different containers and verify they have separate sessions.
Testing CORS from different origins: Test cross-origin behavior within the same browser.
Checking if features work without auth: Open your app in a fresh container to see the logged-out state while staying logged in elsewhere.
Combining with Session Saver
One limitation of containers: if you close Firefox, your container assignments survive, but the tabs themselves don't (unless Firefox is configured to restore the last session).
For teams that work with multiple container contexts and want to save and restore specific container tab sets, Tab Manager & Session Saver saves your tab sessions by name — so you can restore a specific work context later without losing the container assignments on individual tabs.
What Containers Don't Protect Against
- IP address: All containers share the same IP/VPN. Sites can still correlate sessions by IP.
- Browser fingerprint: Containers don't change your fingerprint. A site can still fingerprint you across containers.
- Extensions: Extensions can see tabs across all containers (unless you restrict extension access per site).
For stronger isolation, combine containers with a VPN (different exit nodes per context) or use Firefox's Fission process isolation.
Multi-Account Containers are free, built by Mozilla, and solve a real problem: managing multiple accounts and preventing cross-site tracking without multiple browsers. If you haven't set up your social media and work accounts in containers yet, it's worth 10 minutes.
Top comments (0)