Window Session Manager by Carl Brandenburg

Window Session Manager treats each window as a session: name it once, and its tabs are saved automatically, on every change and when the window closes. Nothing to remember to save.

Sidebar overview. All your sessions in one list, with an indicator showing which are open. Click a closed session to reopen it in a new window; click an open one to jump to it. Expand any session to see its tabs and open just the one you need.

Fast, light restores. Reopened windows load only the tab you were on — the rest stay unloaded until clicked, so even large sessions restore instantly. Pinned tabs and Multi-Account Container assignments are preserved.

Named windows. The session name can be shown in the window title, and survives browser restarts and reopened windows. Works alongside the Window Titler extension: names you've already set there are picked up automatically.

Your data stays yours. Export sessions to JSON (all at once or one at a time) and import them anywhere. Everything is stored locally — no accounts, no servers, no data collection.