What is an Audio Unit Plugin?

An Audio Unit plugin (often abbreviated AU) is a type of audio plugin format developed by Apple for use on macOS and iOS systems. Audio Unit plugins allow additional audio processing tools and virtual instruments to run inside music production software.

Audio Unit plugins can perform many different functions in a music production environment. Some plugins apply audio effects such as equalization, compression, reverb, delay, or distortion, while others act as virtual instruments that generate sound, such as synthesizers, samplers, or drum machines.

These plugins operate within host applications such as digital audio workstations (DAWs), where they can be inserted on audio tracks or MIDI tracks to process or generate sound. Producers can combine multiple plugins together to build complex signal chains for sound design, mixing, and mastering.

Audio Unit plugins are commonly used in macOS-based music production software such as Logic Pro and Ableton Live. Because the format is built directly into Apple’s operating systems through technologies like Core Audio, Audio Units provide efficient performance and deep integration with the Apple audio ecosystem.