OpenVRUI is an object oriented virtual reality user interface API. Its design is scene graph independent, OpenSG and OpenSceneGraph backends are implemented, but only the latter is fully functional. Its syntax resembles GUIs like Java AWT or QT.

The base class of all GUI elements is vruiUIElement.

Events are processed by Actors (e.g., coButtonActor, coSliderActor, coValuePotiActor), which are called on user events. User interface elements defined by the API developer need to be derived from the respective actors in order to receive events.