Zentryx by 6Ff

Zentryx is a calm mode for your browser. Turn on Zen to keep attention on one tab while other tabs are muted and, if you choose, temporarily discarded to free resources. You can lock focus to the current tab or let it follow as you switch. When things get cluttered, Tidy closes duplicates and sorts the rest by site or title so related work sits together. For moments when the page itself is busy, a gentle on-page shade can be toggled on demand to reduce visual noise. No scripts run on websites unless you click to add the shade.

The add-on keeps permissions lean and behavior transparent. It uses tabs to update mute state, reorder and remove tabs, and read active tab information. It uses activeTab to inject the optional shade only after a user action, and storage to remember your preferences. There are no inline scripts, no unsafe innerHTML, no remote resources, and no analytics. All code ships with the add-on to comply with AMO policies. Keyboard shortcuts let you toggle Zen (Alt+Shift+Z) and Tidy (Alt+Shift+Y) instantly.