Privacy policy

This policy covers Kiuas: Contrast Therapy Log for iPhone and Apple Watch (“Kiuas”, “the app”) and this website. Kiuas is made by Michele Cantelli, an independent developer (“I”, “me”). Questions: kiuas@emmekappa.me.

The short version

No account, no sign-in. You never give me your name or email to use the app.
No server. Kiuas has no backend. It doesn’t send your sessions, your heart rate or anything else to me or to anyone else.
No analytics, no ads, no tracking. There is no analytics, advertising or crash-reporting SDK in the app.
Your data lives in three places: your iPhone, your Apple Watch and Apple Health. It leaves them only when you share a file yourself.

Apple Health

Kiuas uses Apple HealthKit, and only with the permissions you grant on the Health screen. You can change them at any time in Settings › Privacy & Security › Health › Kiuas, or in the Health app. Health doesn’t tell apps whether reading was denied: if you deny a type, Kiuas simply sees no data for it and works with less.

What Kiuas reads

Data	What it’s used for
Heart rate	Live on the Watch during a session, for the safety alerts, and afterwards for the summary, the chart and the per-round figures.
Resting heart rate	The recovery check after the cold and the “high heart rate while resting” alert.
Date of birth	Optional. Only your age is used, to suggest your default heart rate limit. You can type your own limit instead.
Weight	The Kiuas calorie estimate. Without it, the estimate assumes 75 kg and shows a wider range.
Workouts	The workouts Kiuas itself saved, to build your history and keep it in step with Health. Kiuas recognises them by its own session identifier and ignores other apps’ workouts.
Active and basal energy	Apple’s calories for a session, shown next to the Kiuas estimate, and copied into a corrected version of a session so it keeps them.

Kiuas doesn’t ask for any other Health data: no heart rate variability (HRV), no sleep.

What Kiuas writes

When a session ends, Kiuas saves one workout in Health (type “Mind and Body”), with one part for each phase. It contains:

start, end and the phases, with their type (sauna, steam room, cold, rest…), round and goal;
heart rate recorded by your Watch during the session;
active energy, either Apple’s or the Kiuas estimate (your choice in Settings › Calories in Health), and basal energy as your Watch records it. Active energy counts toward your Move ring;
some details as workout metadata: the protocol name (including the name of a protocol you created), the factors you logged before starting (water, caffeine, alcohol), whether the session ended early, the Kiuas calorie estimate and its range, and an internal session identifier.

Anything in Health can be read by other apps you allow to read workouts. Keep that in mind for the protocol name and the logged factors.

When you correct a session (move the end, change a phase, drop a round), Health doesn’t allow editing, so Kiuas deletes the workout it wrote and saves a new version with the same data.

The setting “I take heart-rate-lowering medicines” is not written to Health: it stays in the app.

Kiuas follows Apple’s HealthKit rules: health data is never used for advertising, never sold and never shared with third parties.

What stays on your devices

On your iPhone, in the app’s private storage: your session history (times, phases, heart rate statistics, alerts), your protocols, your settings (heart rate limits, age if you typed it, the medicine setting, calorie preferences, the cold-water details you enter for the estimate) and the iOS reports described below.

On your Apple Watch: a journal of each session, written event by event so a session survives a crash or restart, plus a copy of your protocols and settings. After a session is saved to Health its journal is moved to an archive on the Watch, where it stays until you delete the app from the Watch.

In your iPhone’s Keychain: the number of sessions you’ve recorded, used for the 2 free sessions of Kiuas Pro. It’s the one thing that stays after you delete the app.

This data isn’t synced to iCloud by Kiuas. Like any app’s data it can be part of your iPhone or Watch backups, if you make them.

iPhone and Apple Watch

The two apps talk through Apple’s WatchConnectivity, a direct channel between your paired devices. The iPhone sends your protocols and limits to the Watch. The Watch sends the finished session to the iPhone and, during a session, its live state (phase, time, heart rate, alerts) so the iPhone can show it. Nothing passes through a server of mine.

Live Activity and notifications

On iPhone, Kiuas can show a Live Activity on the Lock Screen and in the Dynamic Island, and send local notifications when a phase ends. Both are created on the device: there are no push notifications and no notification server. A Live Activity shows the current phase and time and, during an alert, your heart rate: anyone who can see your Lock Screen can see them too. You can turn Live Activities and notifications off in Settings › Kiuas.

Nothing leaves your devices unless you share it:

Kcal by phase (Settings › Data) exports your last sessions as a CSV file: date, phases, durations, average heart rate, Apple’s and Kiuas’ calories, the alerts, minutes in the heat and your Watch’s battery and temperature state during the session.
iOS reports (Settings › Data) exports the reports described below as a JSON file.

Both go through the iOS share sheet to the place you choose (Files, Mail, another app). From then on that copy is in your hands and under the rules of wherever you put it.

Diagnostics

Once a day iOS can hand the app MetricKit reports: battery use, CPU, memory, launch time, hangs, and crash diagnostics. Kiuas keeps the last 30 only on your iPhone and never sends them anywhere. If you want to help with a bug, you can export them and email them to me. They describe how the app behaved, not your sessions.

Separately, if you turned on Share with App Developers in Settings › Privacy & Security › Analytics & Improvements, Apple may share crash reports and usage statistics with me through App Store Connect, in aggregate and without identifying you. That’s Apple’s system, under Apple’s privacy policy, and you can turn it off there.

On the Watch, Kiuas notes the battery level and the device’s temperature state during a session, to report heat warnings and battery use. These stay with the session.

Kiuas Pro subscription

Your first 2 sessions are free; after that, starting a new session needs the Kiuas Pro subscription (details in the terms of use). Purchases go through Apple’s StoreKit and the App Store:

No payment data passes through Kiuas. Apple handles the payment, renewals, refunds and Family Sharing, under Apple’s privacy policy. Kiuas never sees your name, email, Apple Account or card.
What the app knows is only whether a subscription is active, which it asks StoreKit on the device. The Watch asks StoreKit too, and also gets that same yes or no from your iPhone through WatchConnectivity.
The free session count is a number kept in your iPhone’s Keychain, on the device. It stays there even if you delete sessions or delete the app, so the free sessions can’t be reset by reinstalling. It contains nothing else.
From Apple I only get aggregate sales reports in App Store Connect (how many subscriptions, in which countries). They don’t tell me who you are.

What Kiuas doesn’t do

No account, no login, no server, no cloud of its own.
No analytics, advertising or tracking SDKs; no advertising identifier; no tracking across apps or websites.
No selling or sharing of data with anyone.
No payment data: purchases go through Apple and the App Store.
No location, camera, microphone, contacts or photos.

The scientific sources cited in the app are ordinary links: tapping one opens your browser, and that website’s own policy applies.

Keeping and deleting your data

Delete a session in Kiuas (open it in History, then “Delete session”): it disappears from your history and its workout is deleted from Health too.
If you delete a Kiuas workout only in the Health app, the row stays in your Kiuas history, no longer linked to Health. Delete it in Kiuas as well to remove it completely.
Delete the app from your iPhone and Watch: this removes everything Kiuas stored on them (history, protocols, settings, reports, the session journals on the Watch), except the free session count below. Workouts already in Health stay there until you delete them in the Health app.
The free session count in the iPhone’s Keychain stays after you delete the app, on purpose: it’s what keeps the free sessions from restarting. It’s only a number, with nothing about you or your sessions, and it’s removed if you erase the iPhone.
Revoke access to Health at any time in Settings › Privacy & Security › Health › Kiuas.

Your rights

Because I don’t hold any of your data, there is nothing for me to access, correct or delete on your behalf: you have it all, on your devices. If you write to me by email, I keep the message only to answer you and for as long as the conversation needs. You can ask me to delete it.

Children

Kiuas is not meant for children. Sauna and cold water aren’t either, without an adult.

This website

kiuas.emmekappa.me is a static site: no cookies, no analytics, no forms, no third-party scripts or fonts. It’s hosted on Cloudflare Pages, which processes technical data such as your IP address to deliver the pages and protect them from abuse, under Cloudflare’s privacy policy.

Changes

If Kiuas starts handling data differently, this page changes first, with a new effective date at the top. Significant changes will also be mentioned in the app’s release notes.

Contact

Michele Cantelli · kiuas@emmekappa.me