RescueTime is an app that helps you track your time spent on your computer using a desktop app and browser extension. I've been using it for the past day and it is super helpful to see where it is I am wasting my time when I am on the computer. This allows you to set goals and determine what you want to change in order to be more productive. You can also install RescueTime on your mobile devices to track your time there. The great thing about this is that it's completely free, unless you want to buy Premium services.
I'm definitely keeping this one because I need help with managing my time. You can also block distracting websites. However, the most important feature of this app is being able to see your activity. Whether or not you change your habits to be more productive is up to you! :)