https://www.falstad.com/circuit/
https://www.analog.com/en/design-center/design-tools-and-calculators/ltspice-simulator.html
https://www.kicad.org/download/
http://www.cburch.com/logisim/pt/download.html
http://www.spectrum-soft.com/download/download.shtm
https://www.simulide.com/p/downloads.html
Spice Opus
EasyEDA