KiCad - A Cross Platform and Open Source Electronics Design Automation Suite
LibrePCB - LibrePCB is a free EDA software to develop printed circuit boards.
Fritzing - Fritzing is an open-source initiative to support designers, artists, researchers and hobbyists to...
LTspice - LTspice® is a high performance SPICE simulation software, schematic capture and waveform viewer with enhancements and models for easing the simulation of analog circuits.
XCircuit - XCircuit: Home Page
Autodesk EAGLE - Autodesk EAGLE is an electronic design automation (EDA) software.