Privacy policy

Last updated: 2 October 2026

This is a translation for convenience. In case of doubt, the German version is legally binding: German version.

1. Data protection at a glance

General information

The following notes give you a simple overview of what happens to your personal data when you visit this website. Personal data is any data that can be used to identify you personally.

The Trendcurve app (iPhone and Android) and this website should be considered separately: the app stores your weight and health data on your own device and, only if you switch on the backup on iPhone, in your own iCloud account. For anonymous usage analytics without any health values the app uses PostHog; you can switch it off in the app. Details are in section 7.

Data collection on this website

Data processing on this website is carried out by the website operator. You can find their contact details in the legal notice.

2. Hosting

This website is hosted by Hetzner Online GmbH, Industriestr. 25, 91710 Gunzenhausen, Germany. For details please refer to the provider's privacy policy.

This hosting provider is used on the basis of Art. 6 (1) (f) GDPR. We have a legitimate interest in presenting our website as reliably as possible.

3. General information and mandatory disclosures

Data protection

The operators of these pages take the protection of your personal data very seriously. We treat your personal data confidentially and in accordance with the statutory data protection regulations and this privacy policy.

Controller

The controller responsible for data processing on this website is:

Johannes Müller
Simone-Veil-Strasse 30
53121 Bonn
Germany
Email: [email protected]

4. Data collection on this website

Cookies

Our website uses cookies. Some of them are technically necessary, others are only set with your consent (analytics cookies).

You can change your cookie settings at any time via the cookie banner. Technically necessary cookies are stored on the basis of Art. 6 (1) (f) GDPR. Analytics cookies are only set with your consent (Art. 6 (1) (a) GDPR).

Language selection (cookie "kt_lang")

This website is offered in ten languages: German, English, French, Spanish, Italian, Portuguese, Dutch, Swedish, Norwegian and Danish. If you open the home page without specifying a language, we redirect you to the matching language version based on the language setting your browser transmits (the Accept-Language header). This evaluation happens only when the page is requested; the header is not stored.

If you actively pick a language from the selector in the navigation, we store that decision in a cookie named kt_lang. It contains only the code of the chosen language (for example "de" or "fr"), has a lifetime of one year and allows no conclusions about you as a person. The legal basis is Art. 6 (1) (f) GDPR; our legitimate interest is to serve the website in the language you chose on every visit. You can delete the cookie at any time in your browser settings.

Server log files

The provider of these pages automatically collects and stores information in what are known as server log files, which your browser transmits automatically. These are:

Browser type and version
Operating system used
Referrer URL
Host name of the accessing computer
Time of the server request
IP address

This data is not merged with other data sources. It is collected on the basis of Art. 6 (1) (f) GDPR.

Support form

If you send us a message through the form on the support page, your message and, if you provide it, your email address are transmitted to our inbox via the messenger service Telegram (Telegram FZ-LLC, Dubai) and stored there in order to handle your request. Providing an email address is voluntary and only necessary if you would like a reply. To prevent abuse we keep a count of the messages received from your IP address in memory for a maximum of five minutes. The legal basis is Art. 6 (1) (b) or (f) GDPR (handling your request).

5. Analytics tools

Google Analytics 4

This website uses functions of the web analytics service Google Analytics 4, a service provided by Google Ireland Limited ("Google"), Gordon House, Barrow Street, Dublin 4, Ireland.

Google Analytics uses so called "cookies". These are text files stored on your computer that make it possible to analyse your use of the website.

Purpose of processing: We use Google Analytics to analyse the use of our website in order to improve it and make it more user friendly. Specifically we record:

Page views and time on page
Clicks on app download buttons (as event app_download_click)
Interest in Trendcurve Pro (as event premium_interest)
Interaction with FAQ elements (as event faq_expand)
Clicks on the download banner in blog articles (as event blog_cta_click)
Scroll depth (as event scroll_depth)

Legal basis: Google Analytics is used exclusively with your consent under Art. 6 (1) (a) GDPR. You can withdraw your consent at any time via the cookie banner.

Google Consent Mode v2: We use Google Consent Mode v2. This means Google Analytics only starts collecting data once you have actively agreed via the cookie banner. Without your consent no analytics data is transmitted to Google.

IP anonymisation: We have activated IP anonymisation. Your IP address is shortened by Google within member states of the European Union.

Opt out: You can prevent collection by Google Analytics by:

Choosing "Decline" in the cookie banner
Installing the browser add-on to disable Google Analytics: https://tools.google.com/dlpage/gaoptout

You can find more information about how Google Analytics handles user data in Google's privacy policy.

6. Your rights

You have the right at any time:

To obtain information about the personal data we store about you (Art. 15 GDPR)
To request correction of inaccurate data (Art. 16 GDPR)
To request erasure of your data (Art. 17 GDPR)
To request restriction of processing (Art. 18 GDPR)
To request data portability (Art. 20 GDPR)
To object to processing (Art. 21 GDPR)
To withdraw consent you have given (Art. 7 (3) GDPR)

You also have the right to lodge a complaint with a data protection supervisory authority about the processing of your personal data.

7. Trendcurve app (iPhone and Android)

The Trendcurve app is available for iPhone (iOS) and Android. It has no server of its own, no user account and no advertising. All weight and health data stays on your device and, only if you switch it on on iPhone, in your own iCloud account. Where the two versions differ, the relevant section says so.

What data the app processes

Weight readings you enter manually or import from a file (weight, date, time, optional note).
Weight readings from Apple Health (iPhone) or weight and body fat readings from Health Connect (Android), if you enable the import.
Optional body measurements (for example waist, hips, body fat) and your height, if you provide them.
Your goal (mode, starting and target weight), milestones you reach and trend markers.
Your answers during onboarding (goal and hurdles) as well as settings (reminders, appearance, language, dashboard, Health and backup options).

This data is stored locally on your device and used only to calculate the trend, change, forecast, milestones, balance, monthly reports and, if enabled, BMI. It is not transmitted to us or to third parties.

Apple Health (HealthKit, iPhone)

If you enable the import, Trendcurve reads the data types body mass, body fat percentage and waist circumference from Apple Health, plus active energy for the calorie budget. If you switch on write back, Trendcurve writes the values you entered manually for weight, body fat and waist to Apple Health; calculated values such as the trend weight are never written. Both are voluntary and can be switched off individually. Health data is used exclusively for the functions of the app, never for advertising, marketing or data mining, and is never passed on to third parties. It stays on your device only and is not included in the iCloud backup. You can withdraw access at any time in the Health app under "Data Access & Devices" and remove imported entries in Trendcurve.

Health Connect (Android)

If you enable the import, Trendcurve reads the data types weight and body fat from Health Connect, plus active calories burned for the calorie budget. Without the permission for older data, Health Connect only provides the last 30 days; with it, Trendcurve reads your whole weight history once. If you enable write back, Trendcurve writes your manually logged weight and body fat entries to Health Connect; calculated values such as the trend weight are never written. Both are optional and can be turned off separately. Data from Health Connect is used exclusively for the app's features, never for advertising, marketing or data mining, never sold and never shared with third parties. It stays on your device. You can revoke access at any time in Health Connect under App permissions and remove imported entries in Trendcurve. Trendcurve's use of information received from Health Connect adheres to the Health Connect Permissions policy, including the Limited Use requirements.

iCloud backup (optional, iPhone only)

If you switch on the iCloud backup, Trendcurve stores a copy of your data (readings, body measurements, goal, markers, settings) in the key value store of your personal iCloud account. Transmission and storage are handled by Apple under the iCloud privacy terms; we have no access to it. The backup serves solely to restore your data on your own devices. Values imported from Apple Health are excluded and are not stored in iCloud. You can switch the backup off and delete it at any time under "Export, backup & import".

In-app purchases (Trendcurve Pro)

Purchases and subscriptions are processed through Apple's App Store on iPhone and through Google Play on Android. To check and manage your entitlement, Trendcurve uses the service RevenueCat (RevenueCat, Inc., USA). In doing so a randomly generated anonymous user ID, the App Store receipts or the Google Play purchase tokens, the app version, the language and the device type are processed.

In addition, Trendcurve stores anonymous usage attributes there in order to see which features are used and how regularly the app is opened: whether onboarding and a goal are set up, which features are switched on (reminders, Apple Health or Health Connect, body measurements, photos, calorie budget, BMI, iCloud backup), the chosen unit, language and trend calculation, as well as counts such as the number of entries, the number of days with readings, the length of your streak and the days since your last entry. Only numbers and on/off values are transmitted. Weight values, body measurements, height, year of birth, notes and photos are not transmitted, not even in derived form; no health value can be derived from these attributes.

The legal basis is Art. 6 (1) (b) GDPR (performance of a contract) for handling purchases and Art. 6 (1) (f) GDPR (legitimate interest in improving the app) for the usage attributes. More information: revenuecat.com/privacy.

Export and import

Exports (CSV, JSON, trend image) are only created when you explicitly ask for them and are handed to the app or storage location you pick via the system share sheet. Trendcurve itself transmits nothing in the process. Imported files are read locally.

Widgets (iPhone only)

For home screen and lock screen widgets, Trendcurve keeps a small summary (trend, change, streak, goal) in a protected area that only the app and its widget can read. This data does not leave your device.

Background refresh

With background import enabled, iOS or Android may start the app briefly in the background from time to time in order to fetch new entries from Apple Health or Health Connect. No data leaves your device in the process either.

Notifications

Reminders and import notices are local notifications scheduled entirely on your device. There is no push service and no transmission to any server.

Feedback from the app

If you send feedback through the app, your message, the selected type, the app version and, if you provide it, your email address are transmitted to us via the messenger service Telegram. No further data, in particular no weight data, is transmitted. The legal basis is Art. 6 (1) (b) GDPR (handling your request).

Usage analytics (PostHog)

To understand how Trendcurve is used and why people choose for or against Trendcurve Pro, the app uses the analytics service PostHog (PostHog Inc., USA). The data is processed and stored in the PostHog EU cloud. What is sent: a randomly generated, anonymous user ID (the same one used for RevenueCat), which screens you open, the onboarding steps with your answers about goal and obstacles, when a purchase screen is shown and when a purchase is started, completed or cancelled, the usage characteristics listed under "In-app purchases", plus app version, device type, iOS or Android version, language and the country derived from the IP address. Purchase events such as the start, cancellation or renewal of a subscription and the revenue are sent from RevenueCat to PostHog. If you answer the optional short question about your reason, for example after cancelling, your choice and, if you write one, your comment are sent.

Weight values, body measurements, height, year of birth, notes, photos and data from Apple Health or Health Connect are never sent, not even in derived form. There is no tracking across other apps or websites, no advertising ID and no screen recording.

The legal basis is Art. 6 (1) (f) GDPR (legitimate interest in improving the app). You can object to analytics at any time in the app under "Settings & more → Privacy"; after that the app no longer sends usage data to PostHog. More information: posthog.com/privacy.

In addition, Apple and Google may provide us with anonymised statistics via App Store Connect or the Google Play Console if you have agreed to this in your device settings.

Storage and deletion

Your data remains stored for as long as the app is installed. You can remove it completely at any time under "Settings & more → Export, backup & import → Delete all data" or by uninstalling the app. An iCloud backup is deleted there as well.

Your rights regarding the app

Your health data stays with you alone. Usage data at RevenueCat and PostHog is only linked to a random ID that we cannot link to a person. If you want access to or deletion of this data, send us your anonymous ID, which you can find in the app under "Settings & more → Privacy", by email to [email protected]. The current version of the app privacy policy can be found in the app under "Settings & more", on the App Store and on Google Play.