Greenify

Greenify is an Android app that helps you identify and put the misbehaving apps into hibernation when you are not using them, to stop them from lagging your device and leeching the battery, in a unique way!

Reports

Rick Mendes writes about it here

Tips

• If rooted you get more control
• sometimes the accessibility service turn itself off (when you open the app it should tell you)

make sure to buy the pro version & to install xPosed to benefit from the advanced features otherwise you're really not using the app to its full potential - it probably means you need to flash a custom rom

Download

• Google Play Store
• Fdroid not available