Close Duplicate Sites от Mikhail Danshin

Close Duplicate Sites helps you quickly clean up duplicate tabs.

What it does
- Treats all subdomains as the same site using the base domain (eTLD+1), e.g. mail.google.com → google.com.
- Keeps the active tab for that site and closes the rest.
- Keeps pinned tabs (safety default).

How to use
- Click the toolbar button to close duplicates for the current site in the current window.
- Or right-click a tab to run:
- close duplicates for this site (current window),
- close duplicates for all sites (current window / all windows).

Privacy
- No tracking, analytics, or data collection.
- The add-on downloads the Public Suffix List from publicsuffix.org to correctly detect the base domain and caches it locally.