Downloading reacTIVision 1.5.1 for Mac from the developer's website was possible when we last checked. We cannot confirm if there is a free download of this app available. The application lies within Developer Tools, more precisely IDE.
Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. This free software for Mac OS X is an intellectual property of Martin Kaltenbrunner. The most popular version of the tool is 1.4. The bundle id for this application is com.reactable.reactivision.
From the developer:
reacTIVision is a computer vision framework for the fast and robust tracking of markers attached on physical objects, and the creation of multi-touch surfaces. It was designed for the rapid development of table-based tangible user interfaces. Program its available to free download and his open source.
You may want to check out more Mac applications, such as HexDecBin, wxFormBuilder or Ch, which might be similar to reacTIVision.