The app is RoundR, developed by XDA Senior Member, Mohammad Adib. It is a simple app, very tiny in size, and is open source too. It gives you the option to have the corners of your Android device round this way:
It does look cool, if it doesn’t, still my opinion for you is to give this app a try. If you have a device with a screen large enough, you should surely try it. ‘Cause you lose nothing in trying! It’s totally FREE, also only has a size of 68 KB. So, come on, give it a try. If you like it, good. If you don’t, you can uninstall it.
The app has a simple settings screen. You have options to select which of the four corners you want rounded. You can have all of them or just one, two or three. There’s also an option to keep it in the notifications tray so that you can quickly access it to disable or change it’s appearance. Radius of the rounded corners can be set and you can set it to run automatically every time the phone starts. This app is also runs on Android tablets.
RoundR download:
And some more screenshots:
