Goniometry App is a usable application for all mobile devices. It uses the built-in gyroscope + magnetometer device.

It is a simple tool with goniometry that allows doctors to prescribe rehabilitation exercises and patients to perform them themselves and monitor recovery.

Have clear instructions for your exercises.
See your rehab progress between appointments.
Rest assured that they are not overextending, risking further injury.
Able to use in any comfortable position (lying down, sitting, standing)
Use it on any modern smartphone.
Enter the details of the exercise: articulation, direction of movement, and instructions.
Set exercise target range.

Free application does not require any registration, easy and simple to use.