The Class is the static structure of the system. The diagram illustrates the system classes, attributes, operations and interrelationship between them (Ambler, 2014). The class diagram is divided into two main sections, class name with blue background, attributes beginning with a minus sign (-) indicate a private attribute.The arrows show the associations between classes with labels indicating the nature of the relations. For example, User class is associated with Profile class, it means each user has it is own profile.For simplicity, only the main operations are included in these classes. As in requirements mentioned, the User class has Chat, Post, and Message class. To make the class diagram clearer and easily understood, some operations have been eliminated from the figure.