Privacy Policy

This privacy policy is available in several languages. In case of discrepancies, the German version prevails.

1. Controller

Controller within the meaning of Art. 4 No. 7 GDPR for the BaroWatch app and this website:

Alf Hellmund
Ehrensteinstr. 17
04105 Leipzig
Germany
Email: alf.hellmund@gmx.de

For any privacy question and to exercise your rights, an email to this address is sufficient. No data protection officer has been appointed; there is no obligation to do so (Art. 37 GDPR, Section 38 BDSG).

2. Summary

BaroWatch is an app for iPhone, iPad and Apple Watch that measures and displays air pressure. All calculations run on your devices.

• BaroWatch transmits no data to us or to third parties. There is no server, no account and no iCloud sync.
• There is no tracking, no advertising, no profiling and no third-party analytics or advertising SDK.
• Data is only synchronized between your own devices (section 3.5). Otherwise it leaves the device only when you pass it on yourself: as a data export, as diagnostics data or as a support email.

3. Data in the app

BaroWatch processes the following data exclusively on your devices. We as provider receive none of it unless you send it to us.

3.1 Air pressure (barometer)

BaroWatch reads the air pressure from the device's barometer. The system asks for “Motion & Fitness” access for this. Each reading is stored with time, source and — if known — the altitude above sea level, in the storage shared by the app and its widgets on the device (App Group container). You set how long under Store in Settings (24 hours by default, from 1 hour to 365 days); the app deletes older values itself.

Purpose: to display the air pressure, show it as history, statistics and trend, evaluate the pressure alarm and feed the widgets and complications.

Legal basis: Section 25 (2) No. 2 TDDDG, Art. 6 (1) (b) GDPR; the app reads the sensor only with your “Motion & Fitness” permission (see section 6).

3.2 Location (GPS altitude)

BaroWatch uses location services to determine the altitude above sea level.

Purpose: to convert the measured station pressure (QFE) to sea-level pressure (QNH); on iPhone and iPad also to trigger pressure readings in the background.

• iPhone and iPad: the app asks for “Always” access. This lets it measure in the background as well: location events trigger periodic pressure readings, and after a significant change of location the system relaunches the app. While the app uses location in the background, the system shows the usual location indicator.
• Apple Watch: the app uses location only “While Using the App”.

Only the altitude is stored, never the position. Latitude and longitude are neither stored nor transmitted. Stored are the most recently determined altitude with time, accuracy and the pressure measured with it, and the altitude at each reading (3.1).

You can change or revoke permission at any time in system settings under Privacy & Security → Location Services → BaroWatch.

Without permission, the app shows the uncorrected station pressure (QFE).

Legal basis: Section 25 (2) No. 2 TDDDG, Art. 6 (1) (b) GDPR; the app uses location only with your location permission (see section 6).

3.3 Motion activity and steps

With “Motion & Fitness” access, BaroWatch queries the system for the motion activity (e.g. stationary, walking, driving), the steps and — where the device counts them — the floors of the last hour. These values are used only for this decision and are not stored; the diagnostics log (3.6) may contain the result (e.g. “stationary” or “moved”).

Purpose: to determine whether the device has moved since the altitude was last determined; only then is the altitude determined again.

Legal basis: Section 25 (2) No. 2 TDDDG, Art. 6 (1) (b) GDPR; the app queries this data only with your “Motion & Fitness” permission (see section 6).

3.4 Notifications

If you wish, the app creates local notifications when air pressure changes faster than the threshold you set. The notifications are generated on the device; there are no push notifications via a server.

Purpose: to alert you to a rapid pressure change (pressure alarm).

Legal basis: Section 25 (2) No. 2 TDDDG, Art. 6 (1) (b) GDPR; the app shows notifications only with your notification permission (see section 6).

3.5 Sync between your devices

• iPhone and Apple Watch exchange readings with altitude and the Watch's diagnostics data via WatchConnectivity (Apple framework).
• iPhone and iPad exchange readings via MultipeerConnectivity (Apple framework) over the local network or Bluetooth. The connection is encrypted and requires a six-digit sync code. The system asks for “Local Network” access for this. The devices see the device name iOS provides to the app (without special entitlement only the generic name such as “iPhone” or “iPad”).

No server is involved; data goes directly between your own devices.

Purpose: to show the same readings on all your devices; settings apply per device and are not synchronised; this is also how the Watch's diagnostics data reaches the iPhone's diagnostics data (3.7).

Legal basis: Section 25 (2) No. 2 TDDDG, Art. 6 (1) (b) GDPR; the app uses the iPhone–iPad sync only with your “Local Network” permission and the sync code (see section 6).

3.6 Settings and diagnostics log

The app stores settings (e.g. sampling interval, retention, altitude mode, a manually entered altitude, alarm threshold) on the device. A technical diagnostics log records what the background processes decided (sensor, altitude determination, sync, background refresh, alarm) — without coordinates. It is limited to 512 KB; older entries drop out.

Purpose: to apply your preferences; the diagnostics log makes traceable what the background processes decided when you send diagnostics data (3.7).

Legal basis: Section 25 (2) No. 2 TDDDG, Art. 6 (1) (b) GDPR (see section 6).

3.7 Data export and diagnostics data (only at your request)

• Data export (JSON) in Settings creates a file with the stored readings (pressure, time, source, altitude).
• Send diagnostics creates a file with device model identifier, operating system version, app version, permission states, settings, sensor and altitude state, storage and sync status, the diagnostics log of iPhone and Watch, and the latest readings. Never included: coordinates and the sync code.

Both open the system share sheet; there you choose recipient and channel yourself. There is no automatic sending.

Purpose: The data export lets you use your readings outside the app; the diagnostics data serves to trace and fix an error. If you send it to us, we use it exclusively to handle your request (3.8).

Legal basis: for creating it on the device at your request Section 25 (2) No. 2 TDDDG; for handling it with us Art. 6 (1) (b) GDPR, alternatively (f) (see section 6).

3.8 Support email

If you write to us — from the app's help or directly — we process your email address, your name if given, the content and any attached diagnostics data to answer your request. The mailbox is hosted by the email service GMX, a service of 1&1 Mail & Media GmbH, Montabaur, Germany.

Purpose: to answer your request.

Legal basis: Art. 6 (1) (b) GDPR, alternatively (f) (see section 6).

4. Apple platform services

Apple performs the following processing as an independent controller; we have no influence on it. Apple's privacy policy applies: apple.com/legal/privacy. We receive personal data only with the crash and performance data (4.2); purpose and legal basis are stated there.

4.1 App Store

BaroWatch is distributed via the App Store. Apple handles purchase, download and updates. We receive only aggregated statistics from Apple without personal reference.

4.2 Crash and performance data via Apple

If you have switched on “Share With App Developers” in system settings under Privacy & Security → Analytics & Improvements, Apple provides us with crash reports and aggregated performance data of the app. Without this consent we receive nothing. You can withdraw consent there at any time.

Purpose: to detect and fix crashes and performance problems of the app.

Legal basis: your consent given to Apple, Art. 6 (1) (a) GDPR (see section 6).

4.3 Device backup

If an iCloud backup or a backup to a computer is enabled on your device, the app's data stored on the device — like that of other apps — is part of this device backup. The operating system sets up this backup according to your setting, not BaroWatch.

5. This website

This website is served via GitHub Pages (GitHub, Inc., 88 Colin P. Kelly Jr. Street, San Francisco, CA 94107, USA). When you open a page, GitHub processes technically necessary connection data, including your IP address; according to GitHub, every visitor's IP address is logged and stored for security purposes, even without signing in to GitHub. GitHub processes this data as an independent controller under its privacy statement and states no fixed retention period for these logs; we have no influence on this.

The links in the app under Help open this website in the browser; this section applies to that.

The website sets no cookies, contains no tracking and loads no fonts, scripts or other content from third parties.

The legal basis is Art. 6 (1) (f) GDPR; our legitimate interest is a secure, free and reliable provision of the mandatory information about the app. GitHub is certified under the EU-U.S. Data Privacy Framework (adequacy decision of the European Commission, Art. 45 GDPR). GitHub's privacy statement: docs.github.com.

6. Legal bases

• Processing on your devices and sync between them (3.1–3.6 and creating the data export and diagnostics data in 3.7): the data does not reach us. The app stores and accesses it on the device because this is strictly necessary for the features you expressly use (Section 25 (2) No. 2 TDDDG); insofar as personal data is processed, this is necessary for using the app (Art. 6 (1) (b) GDPR). The app uses the sensor and motion data (3.1, 3.3), location (3.2), notifications (3.4) and the local network (3.5) only with your permission in the system.
• Diagnostics data and support email with us (3.7, 3.8): Art. 6 (1) (b) GDPR (handling your request about the app), alternatively (f) (legitimate interest in answering requests and fixing errors).
• Crash and performance data via Apple (4.2): your consent given to Apple, Art. 6 (1) (a) GDPR.
• Website (5): Art. 6 (1) (f) GDPR.

7. Recipients and transfers to third countries

We do not pass data on to third parties and do not sell data. The only recipients are:

• your own paired devices (3.5);
• the recipients you choose yourself when sharing a data export or diagnostics data;
• our email service GMX (1&1 Mail & Media GmbH, Germany) for support emails;
• GitHub, Inc. (USA) when you open this website (section 5);
• Apple as independent controller for the services in section 4.

A transfer to a third country takes place only when you open this website (GitHub, USA, EU-U.S. Data Privacy Framework) and within Apple's services.

8. Retention and deletion

• Readings: as long as set under Store (24 hours by default, at most 365 days); Delete data in Settings removes them immediately.
• Altitude: the most recently determined altitude, until replaced by a new one.
• Motion activity and steps: not stored.
• Diagnostics log: rolling, at most 512 KB.
• Settings: until you change them or delete the app. Deleting the app removes all of its data from the device.
• Export and diagnostics files for sharing: in the app's temporary directory, which the system cleans up itself; what you passed on is with the recipient you chose.
• Support emails and diagnostics data with us: until the request is closed, then deleted no later than 12 months afterwards.
• Website logs: according to GitHub's rules (section 5).

9. Obligation to provide data

You are under no legal or contractual obligation to provide data. Without “Motion & Fitness” access the app cannot measure air pressure; without location permission it shows only the uncorrected station pressure (QFE); without “Local Network” access there is no sync between iPhone and iPad; without notification permission no pressure alarm.

10. No automated decision-making

There is no automated decision-making, including profiling, within the meaning of Art. 22 GDPR.

11. Your rights

To the extent we process personal data about you (usually only for support requests), you have the right to:

• access (Art. 15 GDPR)
• rectification (Art. 16 GDPR)
• erasure (Art. 17 GDPR)
• restriction of processing (Art. 18 GDPR)
• data portability (Art. 20 GDPR)
• object to processing based on Art. 6 (1) (f) GDPR (Art. 21 GDPR)

Withdrawal of consent (Art. 7 (3) GDPR): you can withdraw consent at any time with effect for the future — permissions for location, Motion & Fitness, local network and notifications in system settings, sharing of analytics data under Analytics & Improvements. The lawfulness of processing before the withdrawal remains unaffected.

You manage the data on your devices yourself: you can export and delete it in the app. Since we do not hold it, we cannot provide information about it or delete it for you.

An email to alf.hellmund@gmx.de is sufficient for any request.

12. Right to lodge a complaint

You have the right to lodge a complaint with a data protection supervisory authority (Art. 77 GDPR), in particular in the member state of your habitual residence. The authority responsible for us is:

Sächsische Datenschutz- und Transparenzbeauftragte
Maternistraße 17, 01067 Dresden, Germany
Postal address: Postfach 11 01 32, 01330 Dresden
Email: post@sdtb.sachsen.de
www.datenschutz.sachsen.de

13. Children

BaroWatch is not directed at children and collects no age information.

14. Changes

We update this privacy policy when app features or legal requirements change. The current version is available at this address and is linked in the app.

Version 2.2, as of 27 October 2026 (replaces versions 2.1 and 2.0 of 26 October 2026 and the version of May 2026).