Breathly - Open-source breath training and relaxation app
Medito - 100% Free Meditation App that will improve your Mental wellbeing with the help of Guided Meditations, Breathing Exercises, Mindfulness Practices, Relaxing Sounds, and more.
Breathwrk - Science backed breathing exercises
Timeless | Meditation - Personal practice meditation timer with guided instruction and multi-day courses.
Box Breathing - Breathe in sync with this to calm yourself down
Breathe Machine - A virtual tool to help with breathing exercises and anxiety.