KiCad - A Cross Platform and Open Source Electronics Design Automation Suite
FreeCAD - An open-source parametric 3D modeler
Proteus PCB design - Proteus PCB design combines the schematic capture and ARES PCB layout programs to provide a...
SolidWorks - Dassault Systèmes SolidWorks Corp. develops and markets 3D CAD design software, analysis software, and product data management software. SolidWorks is the leading supplier of 3D CAD product design engineering software.
QUCS - Qucs, briefly for Quite Universal Circuit Simulator, is an integrated circuit simulator which means you are able to setup a circuit with a graphical user interface (GUI) and simulate the large-signal, small-signal and noise behaviour of the circuit.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.