Flow Keeper by RR88

Flow Keeper helps you enter a calm, uninterrupted work state. Turn on a focus session and the browser will only allow the sites you add to your list, or you can switch to a softer mode that blocks only the domains you select. If you try to wander to another page during a session, you will see a gentle reminder instead of the site so you can return to your task without breaking concentration. A built-in timer keeps the session going for as long as you set and turns the blocker off automatically when time is up. While focus is on, common popups and overlays are hidden and media on open pages is muted and paused to keep noise away. Everything runs locally in your browser, there are no accounts to create and no data is sent anywhere.