OpenSCAD - OpenSCAD is a software for creating solid 3D CAD objects.
FreeCAD - An open-source parametric 3D modeler
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
T-FLEX CAD - Top Systems offers the comprehensive set of integrated applications for T-FLEX Parametric CAD, including CAM, FEA and PDM
KiCad - A Cross Platform and Open Source Electronics Design Automation Suite
ANSYS Workbench - Simulation and Multiphysics platform