I used OpenModelica a number of years ago as a simulink replacement on a project which couldn't afford MATLAB. https://openmodelica.org/ https://openmodelica.o

I used OpenModelica a number of years ago as a simulink replacement on a project which couldn't afford MATLAB. https://openmodelica.org/ https://openmodelica.org/ EDIT: Also, although it's not opensource, I had used Mentor SystemVision eons ago in college. It now has a free web interface. I haven't tried it, but honestly, what could be worse than DxDesigner ;-) https://www.systemvision.com/ https://www.systemvision.com/