Privacy Policy

The short version

The Synesthia app has no analytics, no accounts, no networking, and no third-party SDKs. It does not phone home. Sound reaching the app is turned into numbers — loudness per frequency band — used to draw the next frame, and then discarded. Nothing is written to disk, and nothing leaves your Mac.

What the app does with audio

Synesthia reads short slices of audio a few dozen times a second and runs a Fourier transform over them to get the levels of 64 frequency bands. Those numbers drive the visuals. The audio buffer is overwritten by the next slice.

• Audio is never written to a file.
• Audio is never sent over a network.
• There is no recording feature, and no way to export what was heard.

Permissions, and why each one is asked for

Synesthia asks for a permission only at the moment you choose an audio source that needs it. You can use the app without granting anything — it ships with a demo track, and can open an audio file you pick yourself.

Screen & System Audio Recording

Required to visualize what your Mac is playing. macOS provides no dedicated “capture system audio” API; the only sanctioned route is ScreenCaptureKit, the screen-recording framework, which is why the permission is worded around screen recording. Synesthia attaches the video leg of that capture at 2×2 pixels and discards every frame — it uses the audio only. It never captures, stores, or transmits your screen contents.

Microphone

Required only for the “Audio input” source, so a microphone, line-in, or audio interface can drive the visuals. The input is analysed and never played back or saved.

Automation (Music)

Used only by the version of Synesthia downloaded directly from this site, and only for the “Music app” source: reading the current track’s title, artist, album, and artwork so they can be shown on screen, and sending play, pause, and skip commands. Nothing is written to your library. The Mac App Store version does not include this feature and never sends Apple Events at all.

What is stored on your Mac

Synesthia keeps a small amount of local preference data, readable only by the app, in the standard macOS preferences store. None of it is transmitted.

• Your chosen visualizer, palette, and slider settings.
• Your chosen audio source.
• A security-scoped bookmark to the audio file you last opened, so it can be reopened next launch. This is a macOS-issued reference to that one file — it grants no broader access to your disk.

Deleting the app removes your access to this data; it is never held anywhere else.

This website

The app and the website are separate. This site uses Google Analytics 4 to count visits and understand which pages people read. It is configured with IP anonymisation enabled, and it sets cookies in your browser.

Analytics data is processed by Google; see Google’s privacy policy. You can opt out with Google’s opt-out browser add-on, by blocking the script in your browser, or by enabling Do Not Track / a content blocker. Nothing on this site is linked to anything in the app.

Children

Synesthia is not directed at children and collects no personal information from anyone, including children under 13.

Changes to this policy

If this policy changes in a way that affects what the app does with your data, the date at the top of this page will change and the app’s new behaviour will be described here before, or at the same time as, the release that introduces it.

Contact

Questions about privacy: privacy@synesthia.app. For anything else, see the support page.

Synesthia is made by Jon Jaques.