Mixed In Key Live

Mixed In Key Live is a macOS application for identifying musical information from audio playing on your computer. It displays the track’s key, scale, and BPM, along with a visualizer showing the notes being played.

The product page describes these capabilities:

• Analyzes audio as it plays, including samples and music from sources such as Spotify, YouTube, and production software.
• Shows key, scale, and BPM, with a graphic note visualizer for the notes being played.
• Offers a collapsed menu-bar view that can float over other applications.

To install the macOS app with Homebrew, run brew install --cask mixed-in-key-live. The cask installs the Mixed In Key Live.pkg package. The supplied Homebrew entry specifies macOS as a requirement; it does not state a minimum macOS version.

Sources: Official product page · Homebrew cask