This documentation holds information about the V-Ray Application Software Development Kit also known as V-Ray App SDK or V-Ray Application SDK. It is intended for developers interested in integrating V-Ray into new applications or making some other custom software, be it script or web-based, etc.
If you are interested in evaluating V-Ray App SDK, fill out the Evaluation Request form.
The App SDK can't be used to write custom render plugins (i.e. shaders). If you want to write one, you can use the C++ SDK bundled with V-Ray Standalone, V-Ray for 3ds Max or V-Ray for Maya.