Basechat is “native” social networking app just like whatsapp. Basechat works on android as well as iphone devices. It has all the features of whatsapp and it can be good starting point to have your own whatsapp competitor. Basechat uses solid chat server as backend and its code and interface is at par with whatsapp.
This is a free open source cloud storage and file syncing solution. Either host the cloud storage at your own server or use the one provided by Github or Gitorious to create your own cloud storage service easily and for free.