SketchUp, FreeCAD, Autodesk AutoCAD, SOLIDWORKS, ArchiCAD, LibreCAD, Autodesk Inventor, pCon.planner, Vectorworks, DraftSight, ZWCAD, DeltaCAD, DoubleCAD XT, Visual CADD, A9CAD, BRL-CAD, BricsCAD, Dune 3D, FreeDraft, LiteCAD, CADintosh, IronCAD, TouchCAD, CAD Reader, BabaCAD, ARES Commander, CAD 6, CADKON+, RealCAD, Cycas, DesignCAD, Punch! ViaCAD 2D, RealCADD, BlueCAD 1.0, Mapsoft miniCAD are some alternatives to GstarCAD.