Protractor

Protractor & Angle Gauge is a great tool for measuring any angle or slope.

Protractor and angle gauge allows you to measure any angle or slope. You can measure the angle between any line and a vertical using a built-in gyroscope. Or you can measure an angle based on the photo you made and nodes you selected. You can learn exactly how sloped that Leaning Tower of Pisa actually is. It is possible to recalibrate your device and use some line as a base level for your measurements.