Breathe
Retention breathing, guided.
Rounds of deep breaths, then a hold. Breath U paces you, times the hold and shows what your body did.
Twenty-three techniques, one library.
Oxygen Reset, Calm and Sleep as a start. Each technique has its own page: what it is for, how a round runs, when not to practise it.

Read first, then breathe.
Every technique page explains the pattern, the rounds and the safety notes in plain words. Box Breathing, the Physiological Sigh and Oxygen Reset are free; the rest come with Premium.

Heart rate before, heart rate after.
With your permission Breath U reads heart rate, HRV, resting heart rate and respiratory rate from Apple Health, and shows the response of each session.

A week, a month, a trend.
Activity shows your sessions per week and a 30-day trend of resting heart rate, HRV and respiratory rate. Breath U can also write mindful minutes to Apple Health.
Retention breathing is practised sitting or lying down, never in water, never while driving. Stop when you feel dizzy.