Adobe's XD is coming to Windows within a month or two. It appears to be a good alternative clone of Sketch. http://www.adobe.com/products/experience-design.html

Adobe's XD is coming to Windows within a month or two. It appears to be a good alternative clone of Sketch. http://www.adobe.com/products/experience-design.html http://www.adobe.com/products/experience-design.html (As a primary Windows person, Sketch is one of the things I do envy about having an OS X computer!)