This one claims to be "the app to discover the people you’ve crossed paths with, the people you like, [and] the people you’d like to find again." How does Happn work? Every time you cross paths with someone in real life, their profile shows up on your timeline. When you've both liked each other, you have a Crush, which lets you begin a conversation. Bonus: Happn integrated music to its platform to allow users to add songs onto their profiles and send songs to their Crushes!