App Lock

The app lets you pick from multiple lock options, including password, PIN, pattern and fingerprint protection. You can protect your private images, messages, emails and personal information that you’ve stored in various apps. App Lock requires your email account in case you forget the password or PIN and wish to retrieve it.
 
You can prevent App Lock from allowing apps to be uninstalled and hide PIN touches, so that someone standing next to you won’t see the PIN. It also lets you set a timer for re-locking apps and automatically lock apps after installation. It’s quite easy to use as it arranges all locked and unlocked apps in a neat list, making it easy to spot them.