Privacy Policy

The short version

The Synesthia app has no analytics, no accounts, and no tracking SDKs. 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 no audio, and nothing derived from it, ever leaves your Mac.

There is exactly one exception to “no networking”, and it is described in full below: the version downloaded directly from this site checks this site for a newer version. The Mac App Store version makes no network requests at all.

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)

Optional, and only in the version of Synesthia downloaded directly from this site. Granting it adds play, pause, and skip buttons for your music player and pulls in real album artwork; nothing is written to your library. The track title, artist, and album are shown without this permission in both versions, because the players broadcast them system-wide already.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.

Software updates

The version of Synesthia downloaded directly from this site keeps itself up to date using Sparkle, the standard open-source updater for Mac apps. Periodically, and whenever you choose Check for Updates…, it fetches one file from this site — the appcast — and compares the version in it to the one you are running.

• The request carries nothing but what any HTTP request carries: your IP address and a user agent naming the app and macOS version. It contains no identifier, no usage data, and nothing about your audio, your music, or your Mac's hardware.
• Sparkle's optional system-profiling feature, which would append anonymous hardware details to that request, is switched off.
• Every update is verified against a signature made with a key that never leaves the developer's machine, so a compromised server still cannot ship you code.
• You can turn automatic checking off in the update dialog, after which the app makes no network requests unless you ask it to check.

The Mac App Store version contains no updater — Apple's rules forbid it — and therefore performs no network requests whatsoever. Updates arrive through the App Store like any other app's.

This website

The app and the website are separate. This site uses Google Analytics 4 to count visits and to see which parts of the page people read and which download button they press. It sets cookies in your browser. Google Analytics 4 truncates visitors’ IP addresses before storing them, and does not make the full address available to us.

What is recorded is the page, and these interactions with it:

• Which download button was pressed, and where on the page it was.
• Clicks on links leaving the site, and on the support email address.
• How far down the page you scrolled, and which sections came into view.
• Which of the screenshots in the header you chose to look at.
• Anonymous page-speed measurements — how quickly the page drew and responded — so a performance regression is visible without asking anyone.

None of it identifies you, none of it is combined with anything from the app, and no text you type anywhere is collected — there is nothing on this site to type into.

To opt out: enable Do Not Track or Global Privacy Control in your browser and this site loads no analytics at all — the check runs before the script is requested, so nothing is fetched and no cookie is written. A content blocker or Google’s opt-out add-on works too. Analytics data is processed by Google; see Google’s privacy policy.

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.

No purchases, no accounts, nothing to bill

Synesthia is free. There is no price, no subscription, no in-app purchase, and no trial — so there is no account to create, no payment details to hand over, and no billing data for anyone to hold. Nothing on this page is a paid tier: what the app does with your audio is the same for everyone who runs it.

It is a side project rather than a business, which is the honest framing for the support that comes with it: I read every message and I will do my best to fix what is broken or explain what is happening, but I cannot promise a response time.

Contact

Questions about privacy — or anything else at all — go straight to me at me@jonjaques.com. It is my own address, not a queue. The support page answers the common questions first, and the code is public if you would rather read it than ask.

Synesthia is made by Jon Jaques.