Privacy policy

1. Controller

Nico Gruhn
Gustav-Seitz-Straße 4
68163 Mannheim, Germany
Email: mentrim.app@web.de

2. In short

Mentrim stores your training data only on your device. There is no user account, no tracking, no advertising and no analytics. Data leaves your device only in these cases: when you open the package page, buy a package, restore purchases or redeem a code (then via Apple or Google and our service provider RevenueCat, see section 5); at app start only if you have already bought a package on this device (so that your purchase stays up to date); and when you open a link yourself or send us an email.

3. Data on your device

The app stores in the storage of your device or browser: your settings (appearance, language, goal, study plan, reminder times), your training results (answers, response times, scores, learning progress) and which packages you own. This data is not transmitted to us or to third parties. Storing it is technically necessary to provide the function you requested (Section 25(2) no. 2 TDDDG). In Profile → Your data you can delete your training results or everything the app has saved on the device at any time (purchased packages stay); all data disappears when you uninstall the app or clear your browser's site data.

4. Reminders and speech output

Reminders are local notifications scheduled by your device itself; no server is involved. For listening tasks the app uses your device's speech output. Whether this sends data to the operating system provider depends on its settings and privacy policy.

5. Purchases

You buy packages via the App Store (Apple) or Google Play (Google). Payment and billing are handled solely by Apple or Google; we receive no payment data. So that the app knows which packages you own, we use the service RevenueCat (RevenueCat, Inc., 1032 E Brandon Blvd #3003, Brandon, FL 33511, USA) as a processor (Art. 28 GDPR).

When: The app connects to RevenueCat when you open the package page (to show the price from the store), buy a package, restore purchases or redeem a code. At app start this only happens if you have already bought a package on this device – so your purchase stays up to date, e.g. after a refund or a purchase on another device. If you never open the packages, there is no contact with RevenueCat.

Which data: a random, pseudonymous app user ID (stored on your device; it contains neither your name nor your email address), the store’s receipts and transaction data, device and app information (e.g. operating system, app version, store country) and your IP address.

Legal bases: performance of the purchase contract or pre-contractual steps (Art. 6(1)(b) GDPR); storing the ID on your device is strictly necessary for the purchase you requested (Section 25(2) no. 2 TDDDG).

Transfer to the USA: based on the European Commission’s standard contractual clauses (Art. 46(2)(c) GDPR), which are part of our data processing agreement with RevenueCat.

Storage period: the data is kept as long as it is needed to manage your purchases and then deleted, unless statutory retention obligations apply. On request we delete the data linked to your user ID at RevenueCat; just write to the email address above.

Refund requests: if you request a refund from Apple or Google, the store asks us for information. RevenueCat answers automatically on our behalf with these details about your purchase: that the package was unlocked, that a free version was available before the purchase, and our view on the refund. No training data is transmitted. The legal basis is our legitimate interest in protection against unjustified refunds (Art. 6(1)(f) GDPR); we point this out before the purchase, and the store requires your agreement, which you give by buying. You can object at any time by email.

Redeeming a code opens Apple’s redemption sheet or Google’s redemption page.

6. Community (Discord)

The app contains a link to our Discord server. Only when you tap it does Discord or your browser open, and Discord (Discord Inc., USA) processes data under its own privacy policy. The app itself does not transmit any data to Discord.

7. Feedback

When you send us feedback, the app opens your e-mail program with a prepared message. The app does not send anything itself. You see the message before sending and can change it. Only technical details are prepared: app version, operating system, language and – if you write from within a test – the name of the test, the level and the task number. Your training results are not sent along. We process your e-mail address and the content of your message to answer it and to improve the app (Art. 6(1)(f) GDPR) and delete it when it is no longer needed.

8. App stores, website and browser version

Downloading the app is subject to the privacy policies of Apple (App Store) and Google (Google Play); we have no influence on that processing.

We provide the website mentrim.app (legal texts and help) and the browser version of Mentrim at app.mentrim.app via Cloudflare (Cloudflare, Inc., 101 Townsend St., San Francisco, CA 94107, USA). When you visit them, Cloudflare processes technically necessary data, above all your IP address, to deliver the pages and protect them against attacks. The legal basis is our legitimate interest in providing them securely and reliably (Art. 6(1)(f) GDPR). We have a data processing agreement with Cloudflare (Art. 28 GDPR). Data may be transferred to the USA; Cloudflare, Inc. is certified under the EU-U.S. Data Privacy Framework, for which the European Commission has adopted an adequacy decision (Art. 45 GDPR). The website and the browser version use no analytics, no advertising and no external fonts or scripts; to protect against attacks, Cloudflare may in individual cases set a technically necessary security cookie.

Like the app, the browser version stores your training data only in your browser’s storage (see section 3). If you clear your browser data or use a private window, it is lost. You can find more information in Cloudflare’s privacy policy.

9. Your rights

You have the right to access, rectification, erasure, restriction of processing, data portability and to object (Art. 15–21 GDPR). Please contact the email address above. You also have the right to lodge a complaint with a data protection supervisory authority.

10. Minimum age

The app is intended for people aged 16 and over.

11. Last updated

Last updated: 11 October 2026. We update this policy when the app changes, e.g. if a user account is added.