DateTimer is a countdown Chrome extension by K.cium, available for free. It falls under the Browsers category, specifically Add-ons & Tools. This extension offers various features including custom time setting, periodic cycle repetition, calendar view for scheduling, and flash sale functions, adding versatility to countdown timers.

With DateTimer, users can set countdowns to any event they desire, whether it's a birthday, holiday, deadline, or any other occasion. The timer can be conveniently displayed in the Chrome browser toolbar or in a separate window. Additionally, users have the flexibility to customize the timer's appearance, time, and description, making it a practical tool for staying organized and on top of important dates.