It is the alarm clock using the video of YouTube.
If the time when you set it came YouTube starts.
You can choose your favorite songs from the YouTube.
It starts even if you set it in power-saving modes more than android6.0.
How about waking in favorite music clearly in the morning?

When the radio waves can not reach
When the radio waves do not reach will be a built-in alarm sounds.

When volume setting is off
When volume setting is off CoolAlarm changes volume of it automatically and play music.

To those who did not work with another alarm clock application
A menu to stop Doze mode was added. If you stop Doze mode the application will be started at the desired time in all android.