HoRNet SongKey MK4 is an advanced key recognition tool designed to analyze both audio and MIDI signals with high precision. Beyond simple key detection, it identifies chords and song tempo in real time, providing musicians and producers with detailed harmonic insights. The plugin supports MIDI input and output, enabling seamless integration with MIDI tracks and allowing users to record detected chords for further editing. Additionally, SongKey MK4 offers a standalone version capable of generating MIDI clock signals to synchronize external MIDI hardware or software with live audio inputs.

Featuring improved accuracy, SongKey MK4 employs enhanced chromagram analysis and artificial intelligence to detect chords including sevenths, fifths, and suspended types, as well as dynamic key changes within songs. Its intelligent chord progression model tracks key shifts without manual resetting, making it ideal for complex compositions. The interface displays two chromagrams and a keyboard view, providing a clear visualization of active notes and aiding users in matching samples or acapellas with complementary melodies. The GUI is hardware accelerated, vector-based, and resizable to suit various screen sizes and workflows.

The standalone application extends SongKey MK4’s capabilities by allowing real-time analysis from any audio source or live performance, with MIDI clock output to keep DAWs and sequencers perfectly in sync. This makes it an excellent tool for producers, DJs, and musicians who need to quickly determine a song's key and chord progression without access to instruments. Compatible with macOS and Windows, and supporting popular plugin formats, SongKey MK4 combines sophisticated AI-driven harmonic analysis with user-friendly features to enhance music production and live performance setups.