Kerkythea is a standalone rendering system that supports raytracing and Metropolis light transport, uses physically accurate materials and lighting, and is distributed as freeware. Currently, the program can be integrated with any software that can export files in obj and 3ds formats, including 3ds Max, Blender, LightWave 3D, SketchUp, Silo and Wings3D.

Kerkythea started development in 2004 and released its first version on April 2005. Initially it was only compatible with Microsoft Windows, but an updated release on October 2005 made it Linux compatible. As of January 2016, it is also available for Mac OS X. In May 2009 it was announced that the development team started a new commercial renderer, although Kerkythea will be updated and it will stay free and available. A new version called 'Boost' has been released in 2013.

For more information:

https://en.wikipedia.org/wiki/Kerkythea