KiCad - A Cross Platform and Open Source Electronics Design Automation Suite
Pspice - OrCAD PSpice technology provides the best, high-performance circuit simulation to analyze and refine your circuits, components, and parameters before committing to layout and fabrication
Fritzing - Fritzing is an open-source initiative to support designers, artists, researchers and hobbyists to...
Oregano - oregano - An electrical engineering tool for GNOME
EasyEDA - EasyEDA - Web-based EDA suite; runs in browser.
Circuit Simulator - Animated electronic circuit simulator using ideal components to visualize voltage and current.