Privacy Policy

Last updated: November 2026. This policy applies to the iOS and Android app “Liegestütze Challenge”.

Controller

Josua Sievers
Richard-Wagner-Straße 40
91413 Neustadt
josua.sievers@gmail.com

What data we process

• Account: email address, name and, if available, profile picture from your sign-in (email, Apple, Google and others), or a photo you upload as your profile picture yourself. The app stores only a small, square crop of it.
• Training: your sets (number of reps, duration, date and hour), your daily goal, and the streaks and totals calculated from them. For iOS sets counted with the camera also: how many reps were deep enough, the average pace and the speed of each push up (in metres per second).
• Groups: which groups you are in and with which role; who cheered on whom (to limit it to once an hour) and who gave whom props, with emoji and own text. Own texts are seen only by sender and receiver, in that day's stats.
• Notifications: a push token for your device, if you allow notifications.

Camera and face tracking

On iPhones with TrueDepth, the app uses the TrueDepth camera during a set. It reads only two values from it: how far the nearest surface (your face, forehead or chest) is above the phone, and what share of the image is too close to measure. On iPhones without a TrueDepth camera (e.g. iPhone Duo), the app instead uses ARKit face tracking and Vision face detection (both by Apple, on the device) with the front camera and reads only one value: how high the centre of your face is above the phone. On Android, the app uses the front camera and bundled Google ML Kit face detection. The relative size of a single face in the frame is used to count; the app does not measure metres or exercise form with it and does not save face recordings. Camera images are processed exclusively on your device. No camera images, videos, depth images or face data are stored or transmitted, and the app does not identify anyone.

From these values the app calculates the reps and the values listed under “Training” above; only these are sent to our server. On iOS, the measured distances of the last 20 sets (time, distance or face height in metres, and what share of the image was too close to measure) stay on your device so that counting can be improved. They are not transmitted, not included in backups, and are deleted along with the app. Camera data is not used for advertising or marketing and is not shared with third parties.

Who sees the data

Members of your groups see your name, your profile picture, your daily goal, today's progress, your streaks and totals, and your statistics (including pace and form). Anyone who doesn't share a group with you sees none of it.

Service providers

• WorkOS, Inc. (USA) – sign-in and account management. Data is transferred to the USA on the basis of the EU Standard Contractual Clauses.
• netcup GmbH (Germany) – server on which the app data is stored.
• Cloudflare, Inc. – encrypted backups and DNS.
• Apple Inc. – delivery of push notifications on iOS and, if used, “Sign in with Apple”.
• Google LLC – “Sign in with Google”, if used, and on Android ML Kit and the delivery of push notifications via Firebase Cloud Messaging (using a push token and an installation identifier of the device). ML Kit sends device and app information, an installation identifier, and performance, usage and error data to Google. Camera images and detected face data are not sent to Google. Details: ML Kit data disclosure and Google Privacy Policy.

Legal basis and retention

We process the data to provide the app to you (Art. 6(1)(b) GDPR). It is stored until you delete your account. You can delete your account at any time in the app under Profile → Delete account; this removes all data on our server and your sign-in account. Deleted data may remain in backups for a limited time until they are overwritten.

Your rights

You have the right to access, rectification, erasure, restriction of processing, data portability and to object. To exercise them, write to the email address above. You can also lodge a complaint with a data protection supervisory authority.

No tracking

The app contains no advertising or advertising tracking. On iOS it contains no third-party analytics tools. Diagnostics and usage data from the Android camera SDK are described under “Service providers” above.

The German version of this policy (Datenschutzerklärung) is the binding one.