Logisim - Logisim is an educational tool for designing and simulating digital logic circuits.
BOOLR - Open-source digital logic simulator
Logicly - - Design circuits quickly and easily with a modern and intuitive user interface with drag-and-drop...
Digital Logic Design - Digital Logic Design is a Software tool for designing and simulating digital circuits.
CircuitVerse.org - CircuitVerse is an online community driven platform to design and simulate digital logic circuits.
Wired Logic - Wired Logic is a pixel based logic simulator.