Enable Chrome Site Isolation for Stronger Site‑to‑Site Security

Desired outcome

Turn on Chrome’s Site Isolation feature so each website runs in its own renderer process, limiting the impact of a compromised site on others.

Prerequisites

• Chrome version 63 or later (the flag exists in all recent stable releases).
• Ability to restart the browser (no admin rights required for the user‑level flag).
• Optional: administrative access if you intend to enforce the setting via enterprise policy.

Procedure

1. Open a new tab and navigate to chrome://flags.
2. In the search box, type Site Isolation.
3. Locate the option labeled Site Isolation (usually shown as Strict site isolation or Site Isolation).
4. From the dropdown, select Enabled.
5. Click the Relaunch button that appears at the bottom of the page to restart Chrome.

Expected checks

• After Chrome restarts, open chrome://site-isolation/. The page should show Isolation enabled: Enabled for your profile.
• Open Chrome Task Manager with Shift+Esc. You should see separate renderer processes labeled with each site’s origin (e.g., https://example.com).
• To confirm iframe isolation, load a page that embeds a cross‑origin iframe (for example, a news site that pulls a widget from another domain). In Task Manager, the iframe will appear under its own process distinct from the top‑level frame.

Recovery options

If you notice excessive memory usage, extension incompatibility, or instability:

1. Return to chrome://flags.
2. Set the Site Isolation flag back to Default or Disabled.
3. Click Relaunch to restart Chrome with the traditional process model.

Limitations and verification

Enabling Site Isolation typically raises Chrome’s memory consumption by roughly 10‑20 % depending on the number of open sites. Some legacy extensions that expect shared renderer processes may crash or malfunction. You can verify the current memory impact by comparing Chrome’s memory usage in Task Manager before and after enabling the flag, or by checking the Memory column on the chrome://site-isolation/ page.