Privacy Policy

Chord Trainer ("the App") is a product of Aaron Technologies OÜ, registered in Estonia (Registry Code: 17336129, VAT ID: EE102955587). This privacy policy explains how we collect, use, and protect your information.

1. Data We Collect

1.1 Data Stored Locally (Your Browser)

The App uses localStorage in your browser to store:

• Your practice settings (difficulty, voicing type, notation system)
• Session history (timestamps, scores, chord timings)
• Practice streak data
• Theme preference

This data never leaves your device. It is not sent to any server. You can delete it at any time by clearing your browser data.

1.2 Web MIDI API

If you grant permission, the App accesses your MIDI devices through the Web MIDI API. MIDI data (note on/off events) is processed entirely in your browser and is never transmitted.

1.3 Analytics

We measure two things, both without cookies and without any advertising network. Vercel Analytics counts page views along with country, browser and device type, so we can see how people find the site; it sets no cookie and stores no IP address, deriving a short-lived hash from the request instead. Separately, the practice trainer sends anonymous coach telemetry to our own Supabase database — which exercises were played, how long they took, where a session was abandoned — identified only by a random device ID that is not linked to your name or email. We use it to make the trainer teach better. You can switch the telemetry off at any time under Account → Privacy, without needing an account to do so; the switch covers page-view measurement too, from your next visit onwards.

1.4 Practice data used to improve the coach

To make the practice coach better, we transmit anonymous events about your practice sessions: which block you played, average times, and whether you ended a session early. For this we store a random device ID in your browser — it contains no name, no email and no IP address, and cannot be traced back to you. With an account, your user ID is sent as well so sessions from the same account can be grouped. You can turn this off at any time in your account settings; transmission stops immediately.

1.4 Hosting

The App is hosted on Vercel (Vercel Inc., San Francisco, CA). Vercel may collect server logs including IP addresses for security and performance purposes. See Vercel's Privacy Policy.

1.5 Fonts

All fonts (Source Serif 4, Inter) are self-hosted and served directly from jazzchords.app. No request goes to Google or any other third party, so your IP address is never shared with a font provider.

2. Data We Do NOT Collect

• No account required — accounts are optional and only used for cross-device sync
• No tracking cookies (only essential auth cookies if logged in)
• No personal information
• No audio recordings
• No MIDI data transmission

3. Third-Party Services

4. Your Rights (GDPR)

Under the General Data Protection Regulation (GDPR), you have the right to:

• Access your data — all practice data is in your browser's localStorage. With an account, you can also access your cloud data through your account settings.
• Delete your data — clear your browser data or delete your account. Account deletion removes all cloud-stored data.
• Portability — your browser's developer tools can export localStorage. Account data can be downloaded through your account settings.
• Object — contact us to object to any processing

5. Children's Privacy

The App does not knowingly collect personal data from children under 16. Since no personal data is collected at all, no special measures are required.

6. Changes to This Policy

We may update this policy occasionally. The "Last updated" date at the top indicates the latest revision.

7. Contact

Aaron Technologies OÜ
Sepapaja tn 6
15551 Tallinn, Estonia
Registry Code: 17336129
VAT ID: EE102955587
Email: info@jazzchords.app
Alternative: admin@must-seen.com
Phone: +49 15679 706761
Website: jazzchords.app