Online Countdown Timer

Focus mode & screen wake lock

The Focus button expands the timer to fill your screen using the browser's Fullscreen API where available — handy for kitchen tablets and study sessions. If your browser supports the Screen Wake Lock API, the countdown also asks it to keep the screen on while a timer is running and this tab is visible; the request is released when you pause, reset, or leave the tab. Both features are optional browser capabilities: they fail silently where unsupported and make no difference to the countdown's accuracy, which is computed from wall-clock time even when browser timers are throttled in a background tab.