FreeCAD is a parametric 3D modeling software allows you to create and modify your design by going back into your model history and changing its parameters. FreeCAD is open source (LGPL license) and completely modular, allowing for very advanced extension and customization.
FreeCAD is multiplatfom, and reads and writes many open file formats such as STEP, IGES, STL and others
You can download a free copy of FreeCAD softwares to your PC through the links given below,
FreeCAD software Windows version can be downloaded here
FreeCAD software Ubuntu version can be downloaded here
FreeCAD software MAC OS X version can be downloaded here
If you are interested in FreeCAD development or custumization for your organization, you may download API documents here
