Modelur is described as 'Simple, yet powerful parametric urban design software. Its performance-based nature enables it's users to quickly create massing studies of the proposed development based on key urban design parameters, such as Gross Floor Area or Number of Building Floors' and is an app. There are six alternatives to Modelur for Windows, Linux, Mac, Autodesk 3ds Max and Blender. The best Modelur alternative is CityEngine. It's not free, so if you're looking for a free alternative, you could try Suicidator City Generator or CityCAD. Other great apps like Modelur are Blended Cities, ghostTown and Building Generator.