Simple Spirit Level is an Android app developed by SaltyLab Inc. that measures the angle of surfaces. The app is designed to be straightforward and easy to use. Once launched, you can place your device on any surface, and the app will display the angle of the surface.

One of the best things about this app is that it is completely free and ad-free. You won't be bothered by any unnecessary ads while using this tool. The app is especially useful for those who need to measure angles but don't want to carry around a physical level.

The app displays the angles of horizontal, vertical, radiation, and tangential surfaces. You can easily combine these numbers to determine the angles of any surface. Overall, Simple Spirit Level is a convenient tool for measuring angles that is perfect for both professionals and amateurs.