Napper. is a tiny bit of built-in marketing right in the form of if you have the free version you don't want to pay for it then it has like a whatever is napper.com watermark. I think it's naturally viral though because when I you share something beautiful with other people they usually ask you how you made it and screenshots are something that people share so every time I take a screenshot now it's got this cool gradient background  and I'll send it to my friends or anyone I'm working on a project with who will eventually figure out what kind of app snapper is.