A free program for Android, by Reddish Diamond.

Edge Lighting & Border Light is a free app that allows you to customize your mobile screen with beautiful, curved edges. It’s easy to use, with a simple interface and a wide variety of settings and themes to choose from. It lets you change the color, and width,  of the border light. 

To use this app, you first need to install it. You can then choose the border light theme that best suits your style and personality. You can also set it to appear on your home screen and lock screen.