A free app for Android, by Manuel Wrage.
Hide Navigation Bar — Rootless is a free utility to hide your navigation bar without root on your Android device. This app is developed by a group of developers who want to provide an excellent user experience and, at the same time, they don’t want to push the limits of the system.
On Android, there is a concept of a navigation bar that can be found in most of the apps. It shows the app name and icon at the top of the screen, and it contains the main menu.
In order to make the app more functional, the developers decided to hide the navigation bar on the Android OS. However, they don’t want to remove it completely. So, this app contains a quick settings tile that you can use to hide the navigation bar whenever you want.