An open-source, free circuit simulator
> Qucs is a GPL circuit simulator. And if you want the GUI option, you might want to try out QucsStudio, which uses Qucs under the hood, and is free to use, but binary-only.<p>Huh? I used Qucs many moons ago and it definitely was complete with GUI.<p><a href="https://qucs.sourceforge.net/screenshots.html" rel="nofollow noreferrer">https://qucs.sourceforge.net/screenshots.html</a><p>Unfortunately Qucs is unmaintained, probably doesn't compile anymore on newer distributions and its binaries were therefore removed from many repositories. Another problem: Qucs was released as GPL while QucsStudio, which uses its sources, has been kept closed by the authors; I smell a GPL violation here.