Translation for information only. The German version is legally binding.
In short: Gesello needs no account and shows no ads. The app contains no analytics or tracking tools. This website counts visits anonymously and without cookies using Matomo on our own server (details below).
Controller
Clemens Riemer
Schulstraße 2
47918 Sankt Tönis
Email: dev@gesello.app
This website (gesello.app)
The website is hosted by Hetzner Online GmbH, Industriestr. 25, 91710 Gunzenhausen, Germany (data processing on our behalf). When you visit, the server processes technically necessary data: IP address, date and time, requested address, browser identifier and amount of data transferred. This serves secure operation (Art. 6(1)(f) GDPR). The logs are deleted after 14 days at the latest.
The website sets no cookies for visitors. A cookie is only created when an editor signs in, and serves solely for that sign-in. Fonts and scripts are loaded from our own server, not from third parties.
Visitor statistics (Matomo). To see which pages are read and which links (e.g. from social networks) bring visitors here, this website uses the open-source software Matomo. Matomo runs on our own server at Hetzner in Germany; the data is not passed on to anyone. Matomo sets no cookies and stores nothing on your device. Your IP address is shortened by two bytes straight away (e.g. 192.168.xxx.xxx), so it cannot be linked to you. Recorded are the pages viewed, time on page, the referring page or campaign, browser, operating system, screen size and approximate country. Individual visit data is deleted after 180 days; after that only aggregated figures remain. The legal basis is our legitimate interest in improving the website (Art. 6(1)(f) GDPR); as nothing is stored on or read from your device, no consent under Section 25 TDDDG is required. If your browser sends “Do Not Track”, you are not recorded.
The Gesello app
The app stores settings, favourites, hidden modules and calculation history exclusively locally on your device. This data is not transmitted. You can delete it at any time in the app (clear history, default settings) or remove it by uninstalling. The app calculates on the device and needs no internet connection to do so.
In the web version of the app (app.gesello.app), the numerical values you enter are sent to our own calculation server for processing. They are used only for the response and are neither stored nor analysed. The information on the server above also applies to the web version.
Purchases of Gesello Pro are handled by Google Play or the App Store. Their privacy policies apply; we do not receive any payment data.
Purchase of Gesello Pro
You buy Gesello Pro through the App Store (Apple) or Google Play (Google). Payment and processing are handled entirely by these providers under their privacy policies. We receive no payment or account data. The app only remembers on your device that Pro is unlocked.
So that only genuine purchases unlock Pro, the app sends the store's purchase receipt to our server at www.gesello.app after the purchase. The server checks it with Apple or Google and does not store it; only the result of the check is logged. The receipt contains details of the purchase (order number, product, date, and with Apple also country and price), but neither your name nor payment or account data. If the server cannot be reached, the app keeps the receipt on your device until the check has succeeded. The legal basis is the performance of the purchase (Art. 6(1)(b) GDPR).
Reporting an error in the exam trainer
In the exam trainer you can report an error in a question. The report is used only to fix the error. What is sent: the ID and version of the question, the type of error you chose, your text and a random ID that the app generates once. It has no link to you or your device. An email address is only sent if you voluntarily provide it for follow-up questions.
The report goes to our server at www.gesello.app and from there to the editorial team of the question pool at mygcode.de for review. Our server stores it only until it has been forwarded (at most 30 days), afterwards only whether it arrived. It does not pass on your IP address. The legal basis is your request to report the error (Art. 6(1)(b) GDPR) and, for the optional email address, your consent (Art. 6(1)(a) GDPR). The email address is used only for follow-up questions about this report.
“Report an error” is only available in the apps for iOS and Android. So that only the genuine app can report, it confirms its authenticity the first time you report through a service from Apple (App Attest) or Google (Play Integrity). Our server receives only the result of this check, no information about you or your device.
Contact by email
If you contact us by email, your details are used only to handle your enquiry (Art. 6(1)(b) or (f) GDPR) and are then deleted, unless there is a statutory retention obligation.
Your rights
You have the right of access, rectification, erasure, restriction of processing, data portability and objection. An email to dev@gesello.app is enough. You can also lodge a complaint with a data protection supervisory authority, e.g. the State Commissioner for Data Protection and Freedom of Information of North Rhine-Westphalia.
Last updated: October 2026