Micro-Cap is described as 'Integrated schematic editor and simulator' and is an app in the Education & Reference category. There are more than 25 alternatives to Micro-Cap for a variety of platforms, including Windows, Mac, Linux, Online / Web-based and Android. The best alternative is KiCad, which is both free and Open Source. Other great apps like Micro-Cap are Circuit Simulator (Free, Open Source), QUCS (Free, Open Source), LibrePCB (Free, Open Source) and Autodesk EAGLE (Free Personal).
McCAD 3-SPICE is based on the latest version (3F5) of Berkeley's SPICE 3 and permits interactive mixed mode circuit simulation. It was developed specifically to take advantage of the processing speeds available thus permitting extremely fast simulations.