Separate Work and Personal Browsing in Firefox with Multi‑Account Containers

Desired Outcome

Keep work, personal, banking and other browsing sessions isolated so that cookies, localStorage, IndexedDB and other web‑storage are never shared between them. This protects against accidental cross‑login, keeps private sessions from leaking into work tabs, and makes it easy to switch context without clearing all data.

What is a Container?

A container is a lightweight tab grouping that isolates web‑storage and some request headers. Each container has its own cookie jar, session storage, and IndexedDB database. The browser does not share these between containers.

Why Use Multi‑Account Containers?

• Separation of concerns: work vs. personal vs. banking.
• Reduced cross‑site tracking because third‑party cookies are kept out of the default container.
• Quick switching: click the icon to open a new tab in a chosen container.

Prerequisites

Firefox Version

Version 115 or newer is required. Older releases may not support the extension or may have bugs.

Extension Availability

The Multi‑Account Containers add‑on is available in the official Mozilla Add‑ons store. It can be installed from about:addons or by searching "Multi‑Account Containers".

Procedure

1. Install the Extension

1. Open about:addons in a Firefox window.
2. Search for “Multi‑Account Containers”.
3. Click Add to Firefox, accept permissions, and wait for the installation to finish.
4. Restart Firefox if prompted.

2. Create Containers

After installation, a new icon appears in the toolbar. Click it to open the container menu.

1. Choose Manage Containers.
2. Click Add a Container.
   • Give it a name (e.g., Work, Personal, Banking).
   • Select a color and an optional icon.
3. Repeat for each desired container.

3. Assign Site‑to‑Container Rules

To ensure a site always opens in a specific container:

1. Open a tab in any container and navigate to the site (e.g., https://mail.example.com).
2. Right‑click the container icon on the tab.
3. Select Always open this site in <Container>.
4. Alternatively, open the extension’s Options page and add rules under the Site Rules section.

4. Use Container Tabs

When browsing, click the container icon and choose the desired container before opening a new tab. The icon’s badge will change to the container’s name and color.

Expected Checks

Verify Isolation

Open the same site in two different containers and log in with distinct credentials. Use the Developer Tools (Ctrl+Shift+I) and navigate to Storage to inspect cookies. Each container should list its own cookie set. Logging out from one tab should not affect the other.

Check Tab Badge

Each tab’s icon should display the container’s label. If the badge is missing or shows the wrong name, the tab is not in the intended container.

Recovery & Troubleshooting

Temporarily Disable Container Enforcement

Some sites break when isolated. Right‑click the container icon on a tab and uncheck Enforce container for this tab. The site will load in the default container for that tab.

Clear Container Data

To reset a container’s stored data:

• Open about:preferences#privacy.
• Under Cookies and Site Data, click Clear Data….
• Check Cookies and Site Data and Cache, then click Clear.
• Optionally, delete the container entirely from the Manage Containers page.

Reinstall the Extension

If the icon disappears or containers stop working, remove the add‑on from about:addons and reinstall it.

Limitations & Complementary Tools

• Containers isolate storage but do not hide your IP address or prevent fingerprinting. Combine with Tracking Protection or a VPN for stronger privacy.
• Third‑party services that rely on cross‑site cookies may not function properly in isolated containers.
• Containers are per‑browser profile; they do not extend to other browsers or devices.

Practical Verification

After setting up, run the following quick test:

# Open two tabs in different containers
# Tab 1: Work container – navigate to https://example.com and log in as user A
# Tab 2: Personal container – navigate to https://example.com and log in as user B

# In Tab 1, open Developer Tools → Storage → Cookies
# Verify that only cookies for user A are present
# In Tab 2, repeat – only cookies for user B should appear

# Log out from Tab 1 and confirm that Tab 2 remains logged in

If the isolation test passes, your containers are correctly configured.