Most alarm clocks online are outdated or require sign-up just to set a timer. AlarmOnline24 is different — a free browser alarm clock that works instantly on any device. - Quick presets: 5, 10, 15, 30, 45 min, 1hr, 2hr - Multiple sounds + volume control - Real-time countdown & progress tracker - Dark mode - No download. No sign-up. Ever. Open the tab. Set your alarm. Get back to work.