Diaspora is a nonprofit social networking platform similar to Instagram that you can share your status, images, and see other people’s comment on the material. This tool also ensures the users that it will not sell its member’s information to advertisers. However, unlike the other social networking programs above, it has few users. This program is not widely known in many countries.
A simple chat (slack style) it's enough. Just having the possibility to send messages either single user or team (#channel). But please don't forgive to give an useful appeal to mobile app (worst error of competitors is, have a good app but totally no mobile friendly!) i would expect to have a similar whatsapp or slack app for messaging within the slack mobile app!