Privacy Policy

§ Privacy Policy

Joint privacy policy for the websites www.maikstrings.com, www.maikstrings.de and www.maikstrings.es and all Android apps listed in the table below.

1. Introduction and Scope

Thank you for your interest in our website and apps. The protection of your personal data is very important to us. The processing of your data is carried out in accordance with the EU General Data Protection Regulation (GDPR), the German Federal Data Protection Act (BDSG), the German Digital Services Act (Digitale-Dienste-Gesetz, DDG), and the German Telecommunications Digital Services Data Protection Act (Telekommunikation-Digitale-Dienste-Datenschutz-Gesetz, TDDDG).

This privacy policy applies to:

• our websites www.maikstrings.com, www.maikstrings.de and www.maikstrings.es including all subpages
• our Android apps as listed in the table below (Ad Earnings apps and music apps)

The Windows program Fritten&Fax and the website frittenfax.maikstrings.de are covered by a separate privacy policy: https://frittenfax.maikstrings.de/datenschutz.html

2. Controller

3. Data Protection Officer

A data protection officer has not been appointed because the legal requirements (§ 38 BDSG) are not met. For data protection questions, please contact the controller listed above.

4. Competent Supervisory Authority

5. Definitions

This privacy policy uses the official terms of the GDPR according to Art. 4 GDPR.

6. Legal Basis for Processing

• Art. 6 para. 1 lit. a GDPR – Consent
• Art. 6 para. 1 lit. b GDPR – Performance of contract
• Art. 6 para. 1 lit. c GDPR – Legal obligation
• Art. 6 para. 1 lit. f GDPR – Legitimate interest
• § 25 TDDDG – Access to terminal device information

A. Data Processing on the Website

A.1 Server Log Files

When the website is accessed, technical data is automatically stored: date/time, requested file, referrer URL, access status, browser type, operating system, IP address (anonymized). Legal basis: Art. 6 para. 1 lit. f GDPR. Retention period: max. 7 days.

A.2 Cookies and Local Storage

This website does not set any cookies itself. Only the appearance you have chosen (light/dark, key theme) is stored in your browser’s local storage (localStorage); this is strictly necessary for the function you requested (§ 25 para. 2 no. 2 TDDDG) and is not transmitted to us. Cookies and similar technologies of Google AdSense are set only with your consent (§ 25 para. 1 TDDDG in conjunction with Art. 6 para. 1 lit. a GDPR). You can withdraw your consent at any time with effect for the future by deleting the site data in your browser.

A.3 Google AdSense

A.4 Browser Tuner (Microphone)

The tuner on the Tools page uses your device’s microphone to detect pitch. Access takes place only after you have granted it in your browser and only while the tuner is running. The audio signal is analysed exclusively locally in your browser; it is neither recorded nor stored, nor transmitted to us or to third parties. You can withdraw the permission at any time in your browser settings.

B. Data Processing in the Apps

B.1 Principle and Assignment of the Apps

We do not operate a server of our own for our apps and do not create user accounts with us. Settings, learning progress, alerts and caches are stored exclusively locally on your device. Which further processing takes place depends on the individual app:

• Ad Earnings apps (Ad Earnings Black, Ad Earnings Service & More, Ad Earnings Time, Ad Earnings White): sign-in with Google and retrieval of AdMob reports (B.2), notifications (B.3), advertising (B.4), Firebase (B.5)
• Ad-supported music apps (Capodaster Sheet Pro, Chord Circle, Circle of fifths +, Circle of Fifths Auto, Musik-Tools-Duo): advertising (B.4) and Firebase (B.5); Circle of Fifths Auto and Musik-Tools-Duo additionally use the microphone (B.3)
• Ad-free apps (Chord of a Circle Pro, Circle of a fifth Pro): no advertising; Firebase only (B.5)
• Klang-Regenbogen and Klang-Spektrum: no advertising, no Firebase or other third-party services and no internet permission; only the permissions described in B.3 apply

B.2 Ad Earnings Apps: Sign-in with Google and AdMob Queries

The Ad Earnings apps show you the earnings of your own Google AdMob account. To do so, you sign in with your Google account (Google Sign-In, Google Ireland Limited). The app receives read-only access to your AdMob account (permissions admob.readonly and admob.report) and retrieves account information (e.g. apps and ad units) and report data (e.g. earnings, impressions, eCPM) directly from Google’s servers. This data is only displayed and cached on your device; we do not receive it and do not store it on servers of our own. Your alert rules and settings are also stored locally.

Legal basis: Art. 6 para. 1 lit. b GDPR (providing the function you requested) and Art. 6 para. 1 lit. a GDPR (your sign-in and consent to the permissions). Ending and withdrawal: You can sign out in the app at any time. You can also revoke access in your Google account under “Security” → “Your connections to third-party apps & services”. Local data is removed by clearing the app data or uninstalling the app.

B.3 Permissions: Microphone, Camera and Notifications

Android asks for the following permissions only when you use the respective function. You can withdraw them at any time in the Android settings.

• Microphone (Musik-Tools-Duo, Circle of Fifths Auto, Klang-Regenbogen, Klang-Spektrum): The tuner and the singing and practice functions need the microphone to detect pitch. Access takes place only while the function is active. The audio signal is analysed exclusively on the device; it is neither recorded nor stored or transmitted.
• Camera (Klang-Spektrum): In the teacher area, the camera is used solely to scan QR codes. No images are stored or transmitted.
• Notifications (Ad Earnings apps, Klang-Spektrum): The apps display notifications generated locally on the device (alerts or practice reminders). For this purpose, notifications and, in the Ad Earnings apps, exact alarms are used. Klang-Spektrum reschedules reminders after a device restart (permission “detect restart”).

Legal basis: Art. 6 para. 1 lit. a GDPR (your grant of the permission) or § 25 para. 2 no. 2 TDDDG.

B.4 Advertising (Google AdMob and Mediation Partners)

The apps Ad Earnings Black, Ad Earnings Service & More, Ad Earnings Time, Ad Earnings White, Capodaster Sheet Pro, Chord Circle, Circle of fifths +, Circle of Fifths Auto and Musik-Tools-Duo display advertising. The ads are delivered via Google AdMob; in the process, the advertising ID, IP address and device information may be processed. In Capodaster Sheet Pro, Chord Circle, Circle of fifths +, Circle of Fifths Auto and Musik-Tools-Duo, Google’s consent prompt (User Messaging Platform) obtains your consent where required. The ad-free apps as well as Klang-Regenbogen and Klang-Spektrum do not display advertising.

B.5 Firebase (Google)

We use services of Firebase (Google Ireland Limited). In the process, technical data such as device and software information, an app installation ID as well as times and events of app usage are processed. Which services an app uses:

B.6 Data Security

All data transmissions of the apps are encrypted via HTTPS/TLS.

C. General Information

C.1 Data Transfers to Third Countries

Google services may transfer data to the USA. Legal basis: EU-US Data Privacy Framework (adequacy decision of 10 July 2023) and EU Standard Contractual Clauses according to Art. 46 para. 2 lit. c GDPR.

C.2 Retention Period

• Server log files: 7 days
• Crash reports and performance data (Firebase Crashlytics/Performance): max. 90 days
• Usage statistics (Firebase Analytics): max. 14 months
• Google sign-in (OAuth token) in the Ad Earnings apps: until you sign out or revoke access
• Local app data: until actively deleted by the user
• Light/dark appearance in the browser: until you delete the site data

C.3 Your Rights

• Art. 15 Right of access
• Art. 16 Right to rectification
• Art. 17 Right to erasure
• Art. 18 Restriction of processing
• Art. 20 Data portability
• Art. 21 Right to object
• Art. 7 para. 3 Withdrawal of consent
• Art. 77 Right to lodge a complaint

C.4 Objection to Advertising Mails

The use of contact data published in our legal notice for the purpose of sending unsolicited advertising is hereby expressly objected to.

C.5 No Automated Decision-Making

Automated decision-making, including profiling according to Art. 22 GDPR, does not take place.

C.6 Changes to this Privacy Policy

We reserve the right to adapt this declaration as needed. The version current at the time of your visit applies. As of: September 2026.