QUCS is described as 'The Quite Universal Circuit Simulator (QUCS) is an integrated circuit simulator allowing the simulation and graphical presentation of results of large-signal, small-signal and noise behavior in circuits' and is a circuit simulator in the education & reference category. There are more than 25 alternatives to QUCS for a variety of platforms, including Windows, Linux, Web-based, Mac and Flatpak apps. The best QUCS alternative is Circuit JS, which is both free and Open Source. Other great apps like QUCS are LTspice, Altium Designer, Pspice and Proteus PCB design.