This free coloring book app for adults has a large selection of beautiful, free-to-use mandalas. The user interface is extremely easy to use and you can start coloring right away. It has a variety of different categories to help you find the perfect page to color, including flowers, animals, landscapes, food, and many more.

There is a color palette that allows you to easily pick a color to use for each section. 

This is a perfect app for anyone looking to relax and de-stress from their day. It's also a great way to spend time with your kids or grandkids.