Qt Quick is described as 'free software application framework developed and maintained by the Qt Project within the Qt Framework' and is a UI Design Tool in the Development category. There are three alternatives to Qt Quick for Mac, Windows, Linux, Android and BSD. The best alternative is React Native, which is both free and Open Source. Other great apps like Qt Quick are Felgo (Freemium) and Clutter (Free, Open Source).
Clutter is a GObject-based graphics library for creating hardware-accelerated graphical user interfaces. Clutter is an OpenGL-based 'interactive canvas' library and does not contain any graphical control elements.