V-Ray Application SDK comes packed along with your V-Ray for 3ds Max installation.
The V-Ray Application SDK (AppSDK) allows third-party integrators to create and/or manipulate V-Ray scenes, initiate and control a rendering process that makes use of the V-Ray engine. V-Ray AppSDK provides a high-level API that enables users to load scenes, render them in-process as well as in distributed mode and also manipulate the scene objects known as V-Ray plugins. V-Ray AppSDK can load and save/export .vrscene files exported from DCC applications such as Autodesk 3ds Max, Maya, etc.
The bundled AppSDK binding is for Python 2.7 and 3.8 (since V-Ray 5, update 1.3).
For full documentation of V-Ray Application SDK, please refer to V-Ray Application SDK.
To download SDK samples and sample scenes, you can download and unpack the official V-Ray App SDK build that contains them. Once installed, by default they reside in Program Files > Chaos Group > V-Ray > AppSDK > examples and Program Files > Chaos Group > V-Ray > AppSDK > scenes.