Privacy policy of the “RudelPlan” app
Last updated: 15 November 2026 · applies to the Android app RudelPlan (de.christiankempf.rudelplan). The website is covered by the general privacy policy. In case of doubt the German version prevails.
In short: RudelPlan reads the calendars on your phone and stores its own data on the device. Only the shared pack calendar goes into a storage of your choice (OneDrive, Nextcloud or WebDAV) – end-to-end encrypted. Private events never leave the phone. I run no server and receive no data.
1. Controller
Christian KempfBreitenweg 2, 72406 Bisingen, Germany
E-mail: christian.firmdev@gmail.com
2. Calendars on your phone
With your permission, RudelPlan reads the calendars set up on the phone (for example Google calendars) and shows them arranged by person. If you create an event for several people, the app enters it into their calendars, which then sync via their respective provider as usual. RudelPlan itself sends these events nowhere.
Holidays and calendar import: RudelPlan calculates public holidays on the device; nothing is fetched for this. You choose an .ics file (for example the waste collection calendar) yourself through Android’s file picker; the app reads only that file.
Watch app (optional): If a Wear OS watch is connected to RudelPlan, the phone provides the events of the next seven days (title, time, place, people; other people’s private events only as “Busy”) to the watch via the Wearable interface of Google Play services, usually directly via Bluetooth.
3. What the app stores on the device
- People: names, colours, order and the assignment to calendars.
- Pack calendar: shared events and series.
- Private events: title, symbol, place, note and reminder of private events – on this device only, they never go into the pack folder.
- Settings: for example whose events this phone reminds about.
- Key and sign-in: the pack key, the OneDrive sign-in tokens or the WebDAV credentials, encrypted in the Android Keystore.
4. Shared pack calendar via OneDrive or WebDAV
So that the whole family sees the same pack calendar, RudelPlan creates a folder in your OneDrive. Each device stores its state there and reads the others’. You sign in with your Microsoft account; sign-in runs via Microsoft (login.microsoftonline.com), the files via the Microsoft Graph interface (graph.microsoft.com). The provider is Microsoft Ireland Operations Limited, One Microsoft Place, South County Business Park, Leopardstown, Dublin 18, Ireland. Microsoft’s privacy statement applies.
Nextcloud or WebDAV: Instead of OneDrive you can use a Nextcloud or WebDAV storage of your choice, for example your own NAS. The app then connects directly to that server; no Microsoft sign-in is needed. The operator of the storage is responsible for it – for your own NAS, that is you. If you use credentials instead of a share link, the invitation contains these credentials so the family can join without an account of their own.
What is shared: the pack events, names and colours of the people and short news about newly created events (title, start, who created it) so the other phones can point them out. For private events, only time span and people go into the folder. Syncing happens when the app is opened, shortly after changes and about every 15 minutes in the background (via the Android service WorkManager).
Encryption: Before a state leaves the device, it is encrypted with the pack key (XChaCha20-Poly1305). Microsoft or the storage operator therefore sees no events, names or places, only encrypted files plus the technical details any storage involves (account, file size, time, IP address). The pack key travels only with the invitation you send to your family yourself.
The legal basis is Art. 6(1)(b) GDPR, as there is no shared calendar without this sync. Without signing in, RudelPlan keeps working with the calendars on the phone.
5. Permissions
| Read and write calendar | Showing your calendars and adding events for the selected people (see 2) |
|---|---|
| Internet | Signing in with Microsoft or connecting to the WebDAV storage, and syncing the pack folder, also in the background (see 4) |
| Notifications, exact alarms | Reminders on the minute and notes about new pack events (can be turned off in the settings); both are scheduled by the device, there is no push service |
| Run at startup | So that scheduled reminders survive a restart |
6. No advertising, no analytics
RudelPlan contains no advertising, no analytics tools, no trackers and no crash reporting.
7. Retention and deletion
Data on the device stays until you delete it in the app or uninstall the app. You delete the pack folder in OneDrive or on your storage there yourself; without the pack key its files are unreadable. Android may include app data in your personal device backup if you have enabled this in the system settings.
8. Your rights
As I receive no data from the app, I cannot provide information about it or delete it; you are in control – on your device and in your storage. For questions, contact me at the address above. You may also lodge a complaint with a data protection supervisory authority, for example the one responsible for me: the State Commissioner for Data Protection and Freedom of Information Baden-Württemberg, Lautenschlagerstraße 20, 70173 Stuttgart, Germany.