Download of Twinjack 1.11 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. We recommend checking the downloaded files with any free antivirus. The application is included in Audio & Video Tools. This free software for Mac OS X is an intellectual property of Twinjack.
From the developer:
Twinjack is an application that lets you stream music from Spotify to anyone in the world. Therefore, you can listen to a favorite song with your friends at the same time, as music sounds better when you listen to it together. In short, anything you play will be streamed to your listeners live.
You may want to check out more Mac applications, such as PlayPod, Deezer Radio Player or ffmpeg, which might be similar to Twinjack.