X-FreeCAD (most commonly referred to simply as FreeCAD) is a free, open-source parametric 3D modeler engineered to design real-life objects of any size. The “X” prefix is typically used in specific tech contexts to denote a portable app package (like X-FreeCAD by winPenPack), its underlying X11/Xorg graphics system on Linux systems, or simply its modern 1.x version series. Key Features of FreeCAD