Are imitation apps on windows store legit?

[Christopher]

So I bought the surface 2 because I really prefer it over ipad or any other tablets. Everything about it is better but the app store. The windows store is still not well developed and doesn't have most apps that android and apple store have. Apps like snapchat, vine, instagram, Spotify are not listed in the windows store. Although when I search them up, I get imitation apps that are created by various publishers and have similar themes as the original apps on android and apple, but what bothers me is that you actually get your friends list or play list when you sign in with your legit accounts. What does that mean? Are those imitation apps legit? How do they use my accounts to retriever information from the real app? Are they legal. For example the app called prosnap is an imitation of snapchat. The app called spotlite is an imitation of Spotify. I use them and they really do work, but it scares me how they can retrieve my account info and actually log me in to the legit app. Anyone has any idea?