SlowpulseSlowpulse for iPhone & Apple Watch
Your body notices stress before you do.
Slowpulse learns what your heart does when you're calm — then tells you when it stops doing that, and walks you back down with a breath.
Free to download · no account required · ten languages · iOS 18 and watchOS 11 or later
Inhale
0
Bytes sent off device
14
Day baseline window
10
Languages
100
Percent on-device
How does it work?
Built on your baseline, not a population average.
A resting heart rate of 72 means nothing on its own. It means something if yours is normally 58.
It learns your normal
Slowpulse reads up to two weeks of resting heart rate and HRV from Apple Health. About three days of wear is enough to start scoring — overnight especially.
It watches for drift
Your watch records heart rate every few minutes and HRV a few times a day. Slowpulse weighs each against your baseline — and by how recently it was measured, so last night’s reading isn’t treated as describing right now.
It knows exertion isn't stress
A hard workout raises your heart rate too. Slowpulse discounts the score using active energy and exercise minutes, so a run doesn't read as panic.
It gives you the breath
A guided 4-7-8 cycle with haptics on your wrist. Inhale for four, hold for seven, exhale for eight. No screen required.
On the wrist
The part that matters happens without your phone.
The Apple Watch app reads heart rate and HRV directly, shows your current score, and runs the full breathing exercise with a distinct haptic for each phase — one tap up to inhale, a click to hold, one tap down to exhale.
- Live heart rate and HRV from the wrist sensor
- Your stress score mirrored from iPhone
- Guided 4-7-8 with per-phase haptics
- Works while the phone stays in your pocket
Show your working
See exactly why your score is your score.
Tap the number and Slowpulse shows you its arithmetic: how many points came from your heart rate, how many from your variability, and how far each sits outside your own normal. It says when a workout discounted a reading, and when a variability sample was too old to count. Nothing is rounded away — the parts add up to the number on the ring.
- Every figure measured against your own resting numbers
- Exercise subtracted, because exertion is not stress
- Stale readings lose their weight instead of being carried forward
- Worked out on your iPhone, which is why it can be shown at all
Privacy
Nothing leaves your device. There is nowhere for it to go.
Slowpulse has no account, no server and no analytics. Your heart data is read from Apple Health, scored on your iPhone, and stored on your iPhone. The app makes no network requests of any kind — the only thing it talks to is Apple's own payment system, when you choose to subscribe.
- No sign-up, no email, no password
- No backend to breach — none exists
- No third-party analytics or tracking SDKs
- Delete the app and the data goes with it
When you aren’t looking
The best version of this app is the one you don’t open.
Checking a score is something you have to remember to do. These are the parts that work while the phone is in your pocket.
A Smart Stack card that surfaces
Above your threshold it promotes itself to the top of the stack. Below it, Slowpulse stays out of your way entirely — and a strained reading decays back down instead of pinning there until something dislodges it.
Ask without unlocking
“Hey Siri, what’s my stress?” is answered in place, from the score the app last worked out. Shortcuts can start a breathing session too, so it can hang off an automation or a button.
Ten minutes before it matters
Turn it on and Slowpulse offers the breath in the ten minutes before an interview, a presentation or a review. The window shuts the moment the event starts — interrupting you mid-presentation is the failure this exists to avoid.
Real recovery sessions
Sustained strain offers a genuine workout, scheduled onto your watch. It lands in the Workout app and counts toward your rings, with a heart-rate band worked out from your own resting rate rather than a chart.
Your data, exportable
Every reading exports as CSV or JSON, units named in the header, so the file still makes sense without this app. JSON restores; CSV is the copy that never comes home.
It speaks your language
Ten languages, translated in full rather than machine-passed over the interface — and a picker in Settings if you would rather read it in a language your phone isn’t set to.
Ten languages
Translated properly, not passed through a machine.
Every string in the app — 258 of them — in ten languages, checked for the places a translation silently drops a number or reorders a sentence. Slowpulse follows your device, or you can override it just for this app.
- English
- Deutsch
- Français
- Italiano
- Nederlands
- Español
- Português
- 日本語
- 한국어
- 繁體中文
A stress app that phones home is a strange thing to trust.
You can verify the claim the boring way: put your iPhone in Airplane Mode. Everything still works.
Test the claim yourselfWhy baseline-relative
Three decisions that shape the whole app.
“A normal HRV does not exist. Published values differ by a factor of three between healthy people, so only your own trend carries information.”
Why Slowpulse compares you to yourself, never to a population
“A hard session lowers HRV and raises heart rate, exactly as stress does. A score that cannot tell them apart is measuring your training log.”
Why exercise is subtracted before anything is scored
“Your watch records variability a handful of times a day. Reading last night’s sample as a description of this afternoon is the easiest way to be confidently wrong.”
Why a stale reading loses weight instead of being carried forward
Our pricing plans
Checking your score is always free.
You only pay for the part that works when you aren't thinking about it — being told, and being able to look back.
Free
$0
No account required
- Check your stress score any time
- See exactly how that score was calculated
- Guided 4-7-8 breathing, iPhone and Watch
- Your five most recent events
- Everything stays on-device
Premium
$29.99
per year · renews annually
- Everything in Free
- Stress alerts the moment you drift
- Complete history and trends
- Still entirely on-device
Lifetime
$79.99
once · no subscription
- Everything in Premium
- One payment, kept forever
- All future updates included
- Nothing to remember to cancel
Prices in USD. Payment is charged to your Apple Account; cancel any time in Settings. See Terms.
Why it's built this way
HRV is unusually revealing.
Over weeks, heart rate variability sketches your sleep, your drinking, your illnesses and your bad days at work. Most apps in this category upload it, because uploading it is what makes a dashboard, a leaderboard and a recommendation engine possible.
Slowpulse doesn't do those things, and so it doesn't need the data anywhere but your phone. The scoring is a handful of arithmetic on numbers Apple Health already holds — it does not need a model in a data centre to run. Keeping it local wasn't really a feature decision so much as the absence of a reason to do otherwise.
Know before it gets loud.
A quieter way to notice what your body already knows. Checking your score and the guided 4-7-8 breath cost nothing, and never will — upgrade only if you want to be told without looking.
Questions? [email protected]