One Tab Focus

One Tab is a minimal focus tool that enforces a strict one-tab limit in Firefox. When focus mode is on, any attempt to open a new tab is instantly blocked. No popups, no warnings — it just doesn't happen. Click the toolbar icon to toggle it on or off whenever you need. While you're focused, a stopwatch tracks how long you've been in the zone, and a short message keeps you encouraged as the minutes add up — with new messages at 5, 15, 30, and 60 minute milestones. That's it. No settings, no accounts, no tracking. Just you and one tab. Features • One-click enable / disable from the toolbar • Instant tab blocking — no extra tabs survive • Focus stopwatch that runs in the background • Motivational messages at key milestones • Zero data collected