The Friends utility allows players manage contacts, and to send and receive friend requests in-game. There are tabs for current friends, friend requests received, and friend requests which have been sent but which are awaiting the other player's decision.
Players may send friend requests to any other player as long as they know that player's correct username. When a player accepts a friend request they have received, the two players become friends, and each will appear in the other's list of friends, represented by their avatar, current level and username.
Friends can exchange messages via the Post Office, and can visit one another's zoos by first viewing their list of friends and then clicking the bus icon under the friend they wish to visit. A visiting friend cannot make any changes to a player's zoo, and can only observe it.
In addition to features for in-game friends, ZooMumba encourages players to share the game with other social contacts and provides links to invite friends via e-mail or Facebook.