Lunacy is described as 'native Windows app that opens, edits, and stores .sketch files. And it’s completely free' and is a well-known app in the Photos & Graphics category. There are more than 10 alternatives to Lunacy for a variety of platforms, including Mac, the Web, Windows, iPhone and iPad. The best alternative is Figma, which is free. Other great apps like Lunacy are Sketch (Paid), Adobe XD (Free Personal), InVision (Freemium) and Akira (Free, Open Source).