Your data stays part of your practice—not someone else’s product.

1. Who we are and what this covers

Kyltherm is operated by Ahmed Hashi, of Finland (“Kyltherm,” “we,” “us,” or “our”). Contact us at support@kyltherm.com.

This Privacy Policy applies to the Kyltherm mobile application, its cloud synchronization, subscription access, and related support.

2. Personal data we process

Account and authentication

• Email address and optional display name.
• Kyltherm/Supabase account identifier, authentication provider, and provider identifier.
• Authentication tokens needed to keep you signed in. Native tokens are stored with the device Keychain or Keystore. Passwords are handled by Supabase Auth; Kyltherm does not store your password in plain text.
• If you choose Apple or Google sign-in, the name, email or relay email, and identifier that provider is authorized to share. We do not receive your Apple or Google password.

Session and wellness records

• Cold-plunge or sauna type, date and time, timer mode, exposure and break phases, rounds, active exposure time, and total session time.
• Manually entered water or sauna-air temperature, immersion depth, and timestamped changes to these conditions during a session.
• Optional notes, perceived intensity, shivering intensity, sauna type, and posture.
• Optional age in years (not date of birth), used to estimate maximum heart rate for the experimental strain calculation.
• Optional body mass before and after a sauna session, dry-weighing confirmation, drinks consumed and urine output, with the associated measurement times when recorded.
• Events you record, such as entering or leaving water, standing, or feeling unwell, and optional recovery check-in answers and their timestamps.

Retired measurements: the updated recording flow no longer asks for sauna humidity or bench level and no longer records sustained-shiver onset. Historical sessions or drafts from an earlier app version may still contain these fields and the previously calculated cold-entry count, evaporative margin, effective heat minutes, or time-to-first-shiver metric. They remain part of your stored history and full JSON data export until the relevant session or account is deleted, but are removed from current metric screens and summary CSV columns; they are not silently erased or recalculated. Physical water-entry and exit events are still recorded for immersion timing, cooling load, heart-rate response and recovery timing.

Optional heart-rate and sensor data

• Heart rate in beats per minute, sample times, and whether samples occurred during exposure, break, or an optional seated pre-exposure baseline.
• RR intervals and sensor-contact information supplied by a compatible Bluetooth monitor; recording-quality and coverage indicators; and the sensor category you select.
• Baseline samples and summaries used to compare pre-exposure heart rate with the early exposure response.
• A preferred monitor’s name and device identifier may be stored locally to make reconnection easier; it is not intentionally synchronized with your cloud session history.

Heart-rate, RR, body measurements, symptom-related entries, recovery answers, and inferred physiological results may be sensitive or health data under applicable law. Providing these optional measurements is not required to use an ordinary timer. You can omit them; metrics that need the missing information will be unavailable. Kyltherm does not connect to Apple Health or Health Connect.

Calculated measurements and comparisons

Kyltherm calculates results from your session inputs and sensor recordings, saves per-session metrics, and generates comparisons across sessions. Current calculations may include:

• Cold: Cold-Minute Equivalents (CME, an experimental cooling-load index), baseline-to-early-peak heart-rate response, and heart-rate settling time.
• Heat: age-based heart-rate strain load, heart rate at recorded posture, heart-rate drift and drift rate, body-mass change, and estimated sweat loss and sweat rate.
• Across sessions: averages, sustained peaks, exposure and break summaries, records, temperature trends, legacy temperature-time indexes, and comparisons of heart-rate responses under similar recorded conditions.
• Calculation versions, input snapshots, recording quality, coverage, and reasons a result is unavailable or retired, so saved results can be interpreted.

New sauna comparisons use recorded temperature, sauna type, duration and posture, with sensor and recording-quality rules where relevant; they do not match unrecorded humidity or bench position. Older comparison definitions are kept separate from the updated version. These outputs are account-linked wellness information, not anonymous statistics. They are descriptive or experimental estimates—not measured heat loss, a diagnosis, proof of adaptation, a validated safety score, or clearance to continue an exposure. Kyltherm does not make decisions with legal or similarly significant effects about you from these scores.

Photos

You may take or select one photo for a session. Kyltherm processes only the image you choose, not your full photo library. A copy is kept in app-private files and, during cloud sync, in a private account-scoped Supabase storage area. Newly attached images are resized and re-encoded as JPEGs to avoid retaining camera EXIF/location metadata in the Kyltherm copy. This does not remove identifying details visible in the photograph or change your original library image.

Bluetooth and device permissions

Kyltherm scans for devices that broadcast the standard Bluetooth Heart Rate Service. On older Android versions, the operating system may label the required Bluetooth-discovery permission as location access. Kyltherm does not use Bluetooth scanning to determine or record your location. Camera and photo access are requested only when you choose to attach a photo; microphone access is disabled.

Subscriptions and purchases

• Subscription product, offer, trial, purchase, renewal, cancellation, refund, and entitlement status.
• Store transaction or receipt information and a Kyltherm account identifier used to associate access with the correct account. Superwall receives this account identifier; subscription processing is not anonymous.
• Paywall views and interactions, plus limited app, device, operating-system, locale, region, and network metadata used to operate and measure the subscription experience.

Apple or Google processes payment details. Kyltherm does not receive or store your full payment-card number. We do not intentionally attach session content, age, body measurements, environmental readings, heart-rate or RR samples, baseline or recovery answers, calculated wellness metrics, notes, or photos to Superwall attributes or paywall events.

Technical, diagnostic, and support data

If crash reporting is enabled in your app build, Sentry may receive the app and build version, device model, operating-system version, timestamp, error type, stack trace, and limited network metadata such as IP address. Kyltherm disables default personal-information capture, screenshots, view hierarchy, tracing, and profiling, and removes user, request, breadcrumb, and extra fields from crash events. We do not intentionally attach session measurements, body measurements, baseline samples, recovery answers, or calculated wellness metrics to crash reports. These controls do not make all technical metadata anonymous.

Expo/EAS Update may process technical request information, such as IP address, platform, and app/build version, when checking for or delivering app updates. If you contact us, we process the contact details, message, and attachments you provide.

3. How and why we use data

We use the data described above to:

• create, authenticate, and protect your account;
• run timers; save and synchronize sessions; display charts, history, and statistics; and restore your data;
• connect to the monitor you select and calculate the wellness information you request;
• use temperature, immersion depth, and timing to estimate exposure indexes; age and heart-rate recordings to estimate strain; baseline and exposure recordings to describe heart-rate responses; and body-mass/fluid entries to estimate sweat loss;
• compare your own sessions under similar recorded conditions and show your optional recovery answers;
• retain historical measurements and calculation versions without inventing missing inputs or silently changing past results;
• store and display your optional photos and notes;
• provide, verify, restore, and manage subscription access;
• create exports and sharing files when you request them;
• diagnose crashes, maintain security, prevent misuse, and improve reliability;
• answer support and privacy requests; and
• meet legal obligations and establish, exercise, or defend legal claims.

Where the GDPR or similar law applies, our legal bases may include performance of a contract for the account, sync, app, and subscription features you request; your consent for optional processing where required; legitimate interests in securing and maintaining the service and understanding the subscription flow with minimal data; and legal obligations. Health-related information also requires a separate applicable condition for processing sensitive data. Where we rely on consent for that processing, it must be explicit and specific. Accepting this policy or granting a device permission alone is not consent to every use of health-related data.

You can decline optional Bluetooth, camera, or photo access and continue using features that do not need it. You can stop future sensor collection by disconnecting or forgetting the monitor, and stop providing optional manual measurements or recovery answers. You may withdraw consent without affecting processing already carried out lawfully. Contact support@kyltherm.com for withdrawal or removal of existing optional data; you can also delete the affected session or your account in the app. Stopping collection does not itself erase earlier records.

We do not sell personal data. We do not use your exposure, heart-rate, RR, body-measurement, symptom, recovery, calculated wellness, note, or photo data for targeted advertising.

4. Storage and security

Kyltherm keeps an account-scoped offline copy of session records so it can work through temporary network loss. In current native iOS/Android builds, saved session records, unfinished-session drafts, and stored photo copies use app-level encryption; heart-rate and RR series use an encrypted SQLCipher database. Encryption keys and authentication sessions use native secure storage backed by the device Keychain or Keystore. Temporary decrypted photos or exported files may exist while displaying, uploading, exporting, or sharing. The browser preview does not provide the same app-level local encryption and should not be used on a shared device for sensitive records.

When signed in, session data—including the optional measurements, baseline samples, environmental changes, events, recovery answers, and calculated results described above—synchronizes to your account in Supabase along with heart-rate/RR samples and attached photos. These records are not local-only. Database row-level security and private storage paths restrict ordinary access to the authenticated account. Data is protected in transit using standard transport encryption. Cloud sync is not end-to-end encrypted: authorized backend services can process the records to operate the service. No system can guarantee absolute security.

Profile sign-out attempts to clear the account’s local sessions, unfinished draft, sensor records, and cached photos; the app warns if cleanup fails. Signing out does not delete cloud history. Uninstalling usually removes app-local data but does not delete cloud data. Use Delete account when you want the Kyltherm account and associated cloud data removed.

5. Service providers and disclosures

We provide only the information reasonably needed for these services:

• Supabase — authentication, database, cloud synchronization, private photo storage, and account-deletion functions. Supabase Privacy Policy
• Sentry — privacy-restricted crash and error reporting, when enabled. Sentry Privacy Policy
• Superwall — paywall delivery, entitlement management, purchase observation, and subscription/paywall analytics. Superwall Privacy Policy
• Apple — Sign in with Apple, App Store purchases, subscription management, and related fraud prevention. Apple Privacy Policy
• Google — Google sign-in, Google Play purchases, subscription management, and related fraud prevention. Google Privacy Policy
• Expo/EAS Update — application update delivery and related infrastructure. Expo Privacy Policy

Providers operate under their own terms and, where they process data for us, appropriate processing arrangements. We may also disclose information when required by law, to protect users or the service, during a business reorganization subject to applicable safeguards, or when you direct us to share it.

Kyltherm’s export and sharing tools open your device’s system share sheet. The person or service you select then receives the file or image under their own privacy practices. Sharing is initiated and controlled by you.

6. Retention, export, and deletion

We retain account and synchronized app data while your account is active and as needed to provide Kyltherm. Optional measurements, baseline recordings, events, recovery answers, and saved metric results follow the retention of their session; they are not kept as a separate anonymous research dataset. You can delete individual sessions and photos in the app. A deleted session is hidden from normal app history but its record may remain temporarily for synchronization until routine server cleanup completes.

Account deletion removes the Supabase authentication identity, profile, synchronized sessions and their optional measurements and calculated results, heart-rate and RR samples, and private cloud photos. The app also clears the account’s main local session data, heart-rate database, and account photo folder from that device. Deletion cannot recall files you previously exported or shared.

Limited information may remain temporarily in provider backups, security logs, or records needed for law, fraud prevention, accounting, store transactions, or disputes. Crash, subscription, and provider-side records follow the applicable provider retention. We delete or anonymize data when no longer needed for the purposes described here, subject to those requirements.

Deleting a Kyltherm account does not cancel an App Store or Google Play subscription and does not delete your Apple or Google account. Manage those separately.

Exports

Kyltherm offers a session-summary CSV, a full session-data JSON export, and a per-session heart-rate CSV. The summary CSV includes supported measurements and metric summaries; the JSON includes account/session/heart-rate/RR data and the saved physiology inputs, baseline, environmental changes, events, recovery answers, calculated results, and calculation versions. Photo files and private photo-storage paths are excluded from these CSV/JSON exports. Export files may contain sensitive information. The app attempts to delete its temporary export copy after sharing; interrupted cleanup or copies created by your operating system or selected recipient may remain. Anyone receiving a file you share can read its contents.

See step-by-step account deletion instructions.

7. Your choices and rights

Depending on where you live, you may have rights to access, correct, delete, restrict, or object to processing; receive portable data; withdraw consent; and complain to a data-protection authority.

You can export data and delete your account from the Kyltherm Profile screen. You can delete individual sessions or photos in the app. For another request, email support@kyltherm.com. We may need to verify that you control the account.

If you are in the EEA, you may complain to the supervisory authority where you live or work. In Finland, this is the Office of the Data Protection Ombudsman.

8. International transfers

Our providers and their subprocessors may process data outside your country. Where required, transfers are covered by recognized safeguards such as adequacy decisions, the European Commission’s Standard Contractual Clauses, and corresponding UK or Swiss mechanisms. Contact us for information about safeguards relevant to your data.

9. Children and minors

Kyltherm does not impose a general product age restriction and is not designed specifically for children. If you are under the age of legal majority, a parent or legal guardian should review this policy and the Terms with you, authorize use where required by law, and supervise all cold- and heat-exposure activities.

In Finland, when consent is the legal basis for offering an online service directly to a child, a child aged 13 or older may provide that consent; younger users need authorization from a person with parental responsibility. The applicable age and authorization rules may differ in other countries. We do not knowingly process a minor’s data contrary to applicable law. A parent or guardian may contact us to exercise applicable privacy rights on a child’s behalf.

10. Changes to this policy

We may update this policy when Kyltherm, its providers, or legal requirements change. We will post the revised version with a new effective date and provide additional notice or request consent when required.

11. Contact

Data controller: Ahmed Hashi
Location: Finland
Privacy and support email: support@kyltherm.com