Soundflower is a MacOS system extension that allows applications to pass audio to other applications. Soundflower is easy to use, it simply presents itself as an audio device, allowing any audio application to send and receive audio with no other support needed.
Initial support for the development and maintenance of Soundflower was provided by Cycling '74. Soundflower is an open source project, if you are interested in contributing please feel free to get involved.
Code for the Soundflower project is now hosted at