We’re happy to announce that Rhino 3D now has CityJSON support via Grasshopper. The GH plugin consists out off a small set of components that can expose and bake the stored data. The format in which the data is exposed enables easy integration with both native GH components and other powerful plugins, for example Ladybug.
The pre-build plugin can be found on Food4Rhino. However, the code is open-source and both the source files and experimental (pre) builds are available.