14+ .Sketch File
PNG. A sketch file is a vector graphics file created by sketch, a vector drawing program for mac os x. Amazing collection of free.sketch files downloads and resources for sketch 3 by bohemian.
Sketch is a simple, powerful, and quickly growing vector graphics application used by artists and designers. The previous answers are valid but old. Read here what the sketch file is, and what application you need to open or convert it.
How to open sketch files.
But you don't have a mac. It was first released on 7 september 2010 and won an apple design award in 2012. But you don't have a mac. Lunacy, sketch for windows download url.