Free, open source system extension for routing audio between applications, recording system audio, and more, creating a virtual audio interface with 2 channels.
Soundflower is a free, open source MacOS system extension that creates a virtual audio interface to allow applications to transmit audio to other applications in real-time. Developed by Cycling '74, Soundflower functions as an intermediate step in an audio routing setup, enabling users to take audio output from one app and send it as an input to another app.
Some key features and uses of Soundflower include:
Soundflower installs drivers to create a 2-channel virtual audio device on your Mac. Applications can then transmit audio to this virtual interface where it can be received as an input source by other apps in real-time. This makes it easy to grab audio from anywhere in your system and manipulate it however you like.
Though powerful, Soundflower can have a bit of a learning curve in setting up complex audio routing workflows. So while it's very versatile, it may be overkill for basic tasks. But for advanced audio routing it's an indispensable tool for macOS users and audio production.