Last updated: 4 September 2026.
Song progress, stars, placement results, settings, the child's nickname, accepted imported songs and their sheet photos stay in this browser. Jetten does not require an account. Clearing browser data can remove them.
A parent can download a backup containing progress, nickname, settings, imported scores and sheet photos, then restore it on another device or at another Jetten address. The file is not encrypted. Keep it private and outside this browser. It does not include recordings, recording consent, analytics or device identifiers.
The game listens while a microphone flight is open so it can recognize piano notes. Recordings are not uploaded unless a parent turns on recording sharing in the parent corner. The game works when sharing is off.
When a parent opts in, completed microphone flights may upload a WAV recording, note-detection measurements, device browser details and game events. A recording can contain voices or other room sounds. We use these sessions only to diagnose and improve note detection.
Recordings are kept for no more than 30 days. A parent can delete recordings associated with the current browser at any time from the parent corner. Turning sharing off prevents future uploads.
Anonymous usage sharing is a separate opt-in. It may report events such as opening the app, completing the microphone check, completing the first flight and returning after seven days. These events do not contain audio, the child's nickname or the notes played.
A parent can choose to upload a photo of sheet music for recognition. The server returns the recognized MusicXML and removes the temporary photo and working files when the request finishes, fails or is cancelled. Work interrupted by a server crash is cleaned up when the server restarts. Accepted songs and photos are saved on the device. Only upload music you are allowed to use.
Songs imported before local storage was introduced may still have server copies. The parent corner can copy those songs and photos to this device. Those older server originals are not automatically deleted during migration.
Jetten is operated by Tomas Hajek. For support or privacy questions, email [email protected]. [email protected]
Server-side photo recognition and any opted-in diagnostic processing run on a Hetzner server in Germany. Cloudflare provides DNS, web traffic proxying, and email forwarding. Support emails are forwarded to the operator's Gmail inbox.