WhatsApp is a great messaging app that most probably inspired Apple to create iMessage. The great thing about WhatsApp is that it's available across multiple platforms, it's what has made it so popular. The only problem with WhatsApp is that it's not the very well designed, I'd actually go as far to say it's pretty ugly. Julian Kraske seems to agree too so he's come up with his own design of WhatsApp in his free time. And I've got to say, it looks beautiful. It has a very flat no nonsense design which is perfect when all you need to do is message someone.