The Stealthy app
Your body's signal, made readable.
The app takes what your Stealthy sensor measures and turns it into things you can act on: when to do your hardest thinking, what your meetings cost you, and how much is left in the tank.
- Every number is read against your own usual, never a population average.
- Works with Google and Microsoft calendars.
- Seven languages. Private by design.
Focus index
One tap tells you what your brain is ready for.
Tap Measure and in about half a minute the app takes a fresh heart rhythm reading and scores how ready your nervous system is for demanding work, from 0 to 100. Between taps it keeps a running estimate from your latest synced readings, so the card is never blank.
- The "i" on the card opens a plain-language guide: what it is, what moves it, how to use it.
- Proprietary algorithm driven from various data points collected from the sensor
- The first week or two is the app learning your range, and it says so.
Three states, three kinds of work
Nervous System: Optimal for Deep Work. Your HRV and stress are balanced.
Do the hard thing now: the writing, the strategy, the decision you have been putting off.
Nervous System: Ready. A short breathing reset can lift you into flow.
Good for most work. A two-minute breathing reset often tips you into Flow.
Nervous System: Fatigued. Prioritise recovery before deep-work sessions.
Clear the shallow tasks, take a walk, and measure again before anything that matters.
How to use it
Plan the work around the number.
- 1
Measure before you start
Before a deep-work block, a negotiation or an exam. It takes less time than making a coffee.
- 2
Match the task to the state
High score, hardest task. Low score, lighter work. You stop spending your best hour on email.
- 3
Run a deep work session
Pick 25, 45, 60 or 90 minutes. The app tracks how long you held a flow state and what it cost you, then scores the session's focus integrity.
- 4
Learn your pattern
After a few weeks, Signal tells you your best window of the day and the score above which your sessions actually work.
Stress insights
See your day the way your nervous system lived it.
Stress is read from your heart rhythm, hour by hour, with movement filtered out so a brisk walk never counts as strain. Tap any hour to see what happened. Step back to the week to find your hardest day, or to the month to see the pattern.
- Four plain bands, from Relax to High, in colours you can read at a glance.
- Today against yesterday, this week against last, and both against your own usual.
- A quiet note when a peak lands at an odd time, such as overnight.
Calendar integrations
Find out which meetings cost you.
Connect Google Calendar or Microsoft 365 and your stress trace is laid over your real day. Every meeting shows the stress recorded during it, and every gap shows whether you settled before the next one.
Stress on your calendar
Baseline 34, the median of your last 7 days of readings.
Your calendars
Your calendar never leaves your phone.
- Recurring meetings build a track record, such as elevated in 3 of the last 4 weeks.
- Up to five calendars, each in its own colour: work, personal, shared. iCloud and others connect by private link.
- One switch masks every event title, so blocks read only as busy time.
Energy today
How much is left in the tank.
You wake with a reserve that last night's sleep recharged. Stress and activity draw it down through the day, and calm stretches give a little back. The card shows where you are now, when you peaked, and what kind of work the rest of the day can carry.
- Four drivers, shown honestly: sleep, stress, activity and bonus recovery.
- A recommendation that changes with the zone, from high output to wind-down.
Vitals
Six numbers, read against you.
Heart rate, HRV, blood oxygen, stress, intensity and sleep, each with a seven-day line and a sentence that says where today sits in your own usual range. No population averages, no verdicts on days with no data.
- Live heart rate while you watch, automatic readings while you don't.
- Sleep filed on the day you wake up, with deep, REM and light stages.
- A quiet "N/A" where there's nothing to show, never a fake zero.
Workouts
Starts with a beat. Ends when you do.
Three, two, one, GO: your workout's own silhouette on the brand green. Then one row of labelled controls, your music one tap away without competing for attention, a live route map with effort colouring outdoors, and sets, rests and intervals in the gym.
- Forgot to stop? After a stretch with no movement the app asks "Still working out?" and, unanswered, ends it where the movement stopped.
- Summaries with moving time, splits, elevation, heart-rate zones and a shareable route.
- Apple Music and Spotify controls on the screen you're already looking at.
Signal
Your day, synthesized.
A short morning briefing on your best window and your likely dip, an evening one on what drained you and what to protect tonight, and a weekly report every Monday. Built only from your own numbers, with the reasons one tap away. Your name stays in our database and is never sent to anyone else.
Cycle tracking
Tracking that stays yours.
Log your periods and the app learns your own cycle, predicts the next one, and shows what your heart rate and HRV tend to do in each phase, from your readings, never population data. Phase notes appear where you already look: on your energy, your stress and your workout readiness.
- Shown only when your profile says female, and only on your phone: cycle data never goes to a TV.
- Forgot to close a period? The app asks after your usual length, then tidies up for you.
- Your history survives a reinstall or a new phone.
On the big screen
No screen on your wrist. The biggest screen in the room when it matters.
Stealthy has no display by design. When you train at home, you get one anyway. Step onto the treadmill, roll out the yoga mat or start a set in your home gym, mirror your phone to the TV, and your heart rate, zone and workout stats appear live and large. You see what your body is doing as it happens, without stopping to look at a phone.
- Made for training at home: treadmill, bike, weights, yoga, anything you do in front of a TV.
- AirPlay on iPhone, screen casting on Android. Only the board is shown, nothing else from the app.
- Your numbers stay blurred until you type the code from the TV into your phone, so they only appear on the screen in front of you. Cycle tracking is never sent to a TV.
Private by design
Your data, on your terms.
Sign in your way
Apple, Google or email, and add a second method any time so one person never ends up with two accounts.
Shared phone, separate lives
Every account keeps its own readings, workouts and cycle history on the phone. Switching accounts never mixes them.
Delete means delete
Delete your account from Profile and every row goes with it, on the phone and on our servers.
A wellness tracker, not a medical device
Every guide ends with what the number is not. We'd rather you trust it for what it is.
Learn
Ten plain-language guides, seven languages.
Focus Index, Energy today, stress, heart rate, HRV, sleep, blood oxygen, METs, biological age and your cycle: each explained in five short parts, in English, German, French, Japanese, Simplified and Traditional Chinese, and Arabic.
Ready when you are.
Stealthy is coming to the App Store and Google Play. Leave your email and we'll tell you the moment it lands.