Something not right?

Nothing is showing

Hertzlight needs permission to hear your Mac. The first time you pick System Audio or an app, macOS asks; if you said no, go to System Settings › Privacy & Security › Screen & System Audio Recording and turn Hertzlight on. For a microphone it's Privacy & Security › Microphone. Then play something: the bars only move when there's sound.

Choosing what it listens to

Click the Hertzlight icon in the menu bar and pick a source: System Audio for everything your Mac plays, a single app such as Spotify or Music, or any microphone.

The window

Settings › Window sets where it sits: floating, always on top, on the desktop behind your windows, or behind your desktop icons. If you turned on Click through and can't grab the window any more, open Settings from the menu bar icon and turn it off again. Full screen is in the menu bar menu too.

Which Macs

macOS 14.2 or later on Apple silicon. The iPhone app, when it arrives, needs iOS 17 or later.

Video calls and the iPhone app

Hertzlight Camera and the iPhone app are coming later; they're not in this release.