StemTunes Privacy Policy

Last updated: July 3, 2026

Plain-language policy below. If a sentence here is ever less protective than what the app actually does, the app’s behavior wins.

What we collect

Nothing. StemTunes does not create an account for you, does not ask for your name or email, sets no advertising or tracking cookies, and includes no analytics or third-party trackers. We have no database of users because we have no user records at all.

Your microphone and audio

StemTunes uses your device’s microphone only to draw the live oscilloscope and loudness meter. The audio is read moment-to-moment in your browser to compute the waveform and volume, and each moment’s samples are immediately discarded. No audio recording is ever created, stored, or transmitted — there is no “save,” no upload, and no file kept on your phone.

Your browser will ask permission before the microphone is used, and you can revoke that permission at any time in your browser or device settings.

On-device analysis and AI

All analysis — loudness, the waveform, and any future features such as musical-note or instrument recognition — runs entirely on your own device, inside the browser. No audio, and no information derived from your audio, is sent to us or to any outside service to be processed.

Showing StemTunes on a TV

When you choose to put the display on a TV, what happens depends on the mode you pick:

• Mirror — everything stays on your phone; you mirror your own screen to the TV with your phone’s built-in feature. StemTunes sends nothing anywhere.
• Cast — the live waveform and your settings are sent directly to the Cast device/TV you select, only to draw the display. Nothing is stored, and it does not pass through any StemTunes server.
• Pair — your phone and the TV’s browser connect directly to each other (peer-to-peer) and the waveform is sent straight to the TV to draw it. To help the two devices find each other, Pair mode uses a small “signaling relay” and a public STUN server; these only exchange the technical details needed to open the connection (including device IP addresses, which is inherent to any peer-to-peer connection) and never receive your audio or waveform. The relay is optional and is run by whoever hosts it (for example, your school); Mirror and Cast don’t use it at all.

What is saved on your device

Your preferences — the selected skin, colors, the “Too Loud!” threshold, sensitivity, and which toggles are on — are saved in your browser’s local storage on your device (under keys like stemtunes.settings). This is what lets your setup persist between classes. It never leaves your device, and you can erase it anytime with “Reset all settings” in the app or by clearing your browser’s site data.

Children’s privacy

StemTunes is a tool for teachers and educators. It does not create student accounts, does not identify individual people, and does not collect personal information from anyone — including children. Because no personal data is collected or stored, there is nothing about students to share, sell, or lose. We designed it this way deliberately, with U.S. rules such as COPPA and FERPA in mind.

No tracking, no advertising, no selling data

We do not track you across the web, show ads, or sell or share data — again, because we don’t collect any. In Mirror mode the app makes no third-party network requests at all; the only outside connections are the peer-connection infrastructure described above, used solely to establish a direct link to your own TV.

Permissions you control

• Microphone — used only for the live display; revoke anytime.
• Screen wake lock (on the TV display, where supported) — keeps the screen from sleeping while the scope is up.

Changes to this policy

If this policy changes, we’ll update the date at the top. Because the app stores no contact information, we can’t notify you directly — please check back here.

Contact

Questions about privacy? Email hello@stemtunes.com.

StemTunes is open source; you can review exactly what it does at github.com/rhino11/stemtunes.