The "Callibri Biofeedback" system is designed for self-regulation training sets prepared by specialists with a goal of being able to manipulate the body's systems at will. The application works with "Callibri" sensor that instantly evaluates muscle tone level (the EMG signal) and the app visualizes muscle activity in the form of a game situation. The Callibri Biofeedback system is used for: • restoration of weakened muscles in stroke and cerebral palsy; • training, increasing the strength and