OptiX is described as 'provides a simple, recursive, and flexible pipeline for accelerating ray tracing algorithms. Bring the power of NVIDIA GPUs to your ray tracing applications with programmable intersection, ray generation, and shading' and is an app in the Photos & Graphics category. There are five alternatives to OptiX for Mac, Windows, Linux, Self-Hosted solutions and Blender. The best alternative is Cycles Renderer, which is both free and Open Source. Other great apps like OptiX are Mitsuba (Free), YafaRay (Free, Open Source), Radeon ProRender (Free, Open Source) and OSPRay (Free, Open Source).
Cycles is Blender’s ray-trace based production render engine and in development since 2011. It was originally developed by Brecht van Lommel, and is maintained by an active team of developers today. Since its release as Apache 2.
Physically based renderer. Mitsuba is an extensible rendering framework written in portable C++. It implements unbiased as well as biased techniques and contains heavy optimizations targeted towards current CPU architectures.
YafaRay is a free open-source montecarlo raytracing engine released under the LGPL 2.1 license. Raytracing is a rendering technique for generating realistic images by tracing the path of light through a 3D scene.