It is quite difficult—just not necessarily in terms of code. What makes it really hard is the chicken-egg problem that people won't come to it until there are p

It is quite difficult—just not necessarily in terms of code. What makes it really hard is the chicken-egg problem that people won't come to it until there are people on it to browse, and there aren't people on it to browse if nobody signs up. OKCupid's clever bypass for this was to get people hooked answering all those little questions. Heck I knew early adopters that signed up just to answer those questions, not necessarily for dating, and then fell into using it. Tinder's was the swipe right/left that has now become a term used outside of the app in other parts of life.