There's science behind how it works... it runs at a rate of six breaths per minute, which was found in scientific studies to be the sweet spot to trigger a "relaxation response" in the brain and body.
Deep breathing has many positive benefits for mental and physical health, and has been shown to lower blood pressure, reduce heart rate, relax muscles, decrease stress and anxiety, and increase energy levels.
One of the biggest benefits is reducing stress. Being stressed keeps your immune system from working at full capacity, which can make you more susceptible to numerous conditions.
I've had a simple version of this running on my computer for a couple of years now and use it pretty much every day. It's also useful as a meditation aid, to bring your focus back to the present moment, and to get yourself into the flow state.
Hope you find it useful too :)
P.S. Would love to hear any thoughts or suggestions. Next up I'm thinking dark mode, maybe personal stats etc. Also, this is a responsive web app so it can be added to your home screen to function as a native app.