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.

Logisim - Logisim is an educational tool for designing and simulating digital logic circuits.

Circuit Simulator - Animated electronic circuit simulator using ideal components to visualize voltage and current.

Digital Logic Design - Digital Logic Design is a Software tool for designing and simulating digital circuits.

Circuit Tree - Design and order Boards in Minutes

BOOLR - Open-source digital logic simulator