Smartapp that alerts me if any of my devices are powered on

need guidance as to which smartapp I can look into to notify me if any of my “THINGS” are powered on (possibly left on by people at the house).

thanks in advance for your kind inputs.

Have look at CoRE.

It can be used to do rule based monitoring and alerting. For example.

Socket 1 has been on for more than 3 hours
Send push notification.