What it does with the music you play
This page exists because the honest answer is short and nobody should have to take it on trust. karanow listens to what your Mac is already playing. Here is where that sound goes, what is kept, and what leaves the machine.
It is processed on your Mac and then it is gone
Sound arrives from the application you are playing from and goes into a rolling window in memory — 1.5 seconds wide, moving forward every 1.125 seconds. The separation model runs on that window, the result is played, and when the window moves on the old audio is not kept anywhere. It is not written to disk. It is not sent to a server. There is no server-side audio processing in any version of karanow.
The model doing the work is HTDemucs, re-exported for low latency and shipped inside the app. It runs on the CPU of your own machine, which is also why karanow needs Apple Silicon: the budget is 1.125 seconds of separation for every 1.125 seconds of music, and an M2 Max spends 268 ms of it.
The only thing written to disk is your own voice
If you press record, that take is written to an m4a file on your Mac and nowhere else. It contains you singing — the microphone signal — and you can play it back or delete it from the recordings window, or find it in the Finder and delete it there.
Nothing else is stored as audio. Not the music you played, not the backing track that came out of it, not a cached copy of either.
What leaves the Mac is a few words of text
When the application you are playing from publishes what it is playing, karanow sends the title, artist, album and duration to third-party services to look up matching information. That is text. No audio is included, and no identifier of yours is attached.
Beyond that, the app talks to karanow’s own entitlement API to check whether your subscription is active, and to Apple’s subscription page if you ask it to open one. There is no analytics SDK, no crash reporter and no usage tracking in the app.
No file comes out at the other end
The backing track exists while it is playing. karanow does not export it, does not save it, and offers no way to get it as a file. This is a real limitation and it is worth being clear about rather than discovering after you have downloaded it: if what you want is a stem you can keep, an offline separation tool is the right thing to use and will give you better quality besides, because it can spend minutes on a track instead of milliseconds.
We do not supply the music
karanow has no catalogue and no library. The music is whatever you are already playing, from whatever you already pay for. It reads the system output stream rather than any application’s interface, which is why it works the same with Apple Music, Spotify, a browser tab or a video player, and why none of them has to know it exists.