Set a timer for 20 seconds to wake you up in 20 seconds. This is a free and easy-to-use countdown timer that allows you to set the hour, minute, and second for the online countdown. Simply start the timer, and it will alert you when 20 seconds have passed. Alternatively, you can set a specific date and time to count down to (or from) an event. Begin your 20 seconds timer now for a quick and precise reminder.