FreeCAD - An open-source parametric 3D modeler
KiCad - A Cross Platform and Open Source Electronics Design Automation Suite
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.
Proteus PCB design - Proteus PCB design combines the schematic capture and ARES PCB layout programs to provide a...
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
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.