Live breath detection and biofeedback from a phone microphone
On-device breath detection from microphone audio with state machine, no wearables or cloud needed.

Accelerometer-based breathing detection beats wearing a chest strap or buying a $320 RESPeRATE device.
People with anxiety, stress, cluster headaches, or anyone wanting HRV-focused breathing exercises
Breathwrk · RESPeRATE · Calm
there is nothing to install, no account, just a web page.
You lie down, put the phone face-down on your chest and tap start.
It listens to your breathing through the accelerometer for a minute, then plays two tones - one for the inhale, one for the exhale - and slowly stretches them out until you're around six breaths a minute. Fifteen minutes total.
Six breaths a minute is roughly the resonance frequency of your cardiovascular system. At that rate with a long exhale your heart rate variability, blood pressure, and breathing sync up and your vagal tone climbs. There's real research behind this going back to Lehrer and Vaschillo in the early 2000s. It's also what a $320 FDA-cleared device called RESPeRATE does and the patent expired, the protocol is in the public domain, it's two tones and a timer.
Most people here are spending all day half-stuck in sympathetic overdrive, context switching, babysitting AI output, managing forty seven tabs. This is the cheapest lever I know of to come down from that. The heart rate drops and your head clears.
The real reason I built it was an accident. I was trying to manage stress based on some info I got online about vagal tone. I have cluster headaches and started coming out of them but have been nagged by these rebound headaches so I dropped the BPM to 5 to see what would happen and low and be hold the damn things went away.
I now enjoy the slow breathing, its one of the things that helps me but honestly that took years of hyperbaric oxygen therapy and diet changes and a lot of work to get there, I'm not saying this does anything for your headaches.
What I will say is that slower breath, lower heart rate, more parasympathetic activation is worth something on its own (look it up yourself) if you're just wrecked at the end of the day.
RE: technical stack -- There is no login by design, no email, no ads. Session history lives in your browser, never leaves your device. None of your breathing data goes anywhere.
I love the idea of this being a PWA so it installs to your home screen and works offline. I put the source on GitHub, link in the footer.
If you have high blood pressure or heart issues it's an add-on, not a substitute.
Its a totally free thing, and based on the current HN community vibe I figured it could help some folks, no matter your socioeconomic status.
Open to feedback and other ideas to improve this.
On-device breath detection from microphone audio with state machine, no wearables or cloud needed.
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