YafaRay is a free, open source ray tracing program that uses an XML scene description language. It has an addon for the 2.78 version of the 3D modelling software Blender. It is licensed under the GNU Lesser General Public License (LGPL).

YafaRay's predecessor YafRay (Yet Another Free Raytracer) was written by Alejandro Conty Estévez, and was first released in July 2002. The last version of YafRay was YafRay 0.0.9, released in 2006. Due to limitations of the original design, the raytracer was completely rewritten by Mathias Wein. The first stable version of the new raytracer, YafaRay 0.1.0, was released in October 2008.

For more information:

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