A full parametric model. All FreeCAD objects are natively parametric, which means their shape can be based on properties or even depend on other objects, all changes being recalculated on demand, and recorded by the undo/redo stack. New object types can be added easily, that can even be fully programmed in Python
A modular architecture that allow plugins (workbenches) to add functionality to the core application. Those extensions can be as complex as whole new applications programmed in C++ or as simple as Python scripts or self-recorded macros. You have complete access from the Python built-in interpreter, macros or external scripts to almost any part of FreeCAD, being geometry creation and transformation, the 2D or 3D representation of that geometry (scenegraph) or even the FreeCAD interface
Import/export to standard formats such as STEP, IGES, OBJ, STL, DXF, SVG, STL, DAE, IFC or OFF, NASTRAN, VRML in addition to FreeCAD's native Fcstd file format. The level of compatibility between FreeCAD and a given file format can vary, since it depends on the module that implements it.
A Sketcher with constraint-solver, allowing to sketch geometry-constrained 2D shapes. The sketcher currently allows you to build several types of constrained geometry, and use them as a base to build other objects throughout FreeCAD.
A Robot simulation workbench that allows to study robot movements. The robot workbench already has an extended graphical interface allowing GUI-only workflow.
A comfortable new workbench for creating traditional drawing sheets with options like detail view, cross sections, dimensioning and others, that permit to put 2D views of your 3D models on a sheet. This workbench then produces ready-to-export SVG or PDF sheets. There exist still the older Drawing Workbench with its sparse Gui-commands but a powerful Python functionality.
A Rendering workbench that can export 3D objects for rendering with external renderers. Currently only supports povray and LuxRender, but is expected to be extended to other renderers in the future.
An Architecture workbench that allows BIM-like workflow, with IFC compatibility.
Path Workbench dedicated to mechanical machining like milling (CAM), and is able to output, display and adjust G code.
