The dissertation looks at the information system (IS) that can provide private and public chat environment known as 'Instant Messenger' (IM). The issues of the IM project management are addressed; literature is reviewed on the features of messenger servers, security aspects of instant messaging, etc. The methods of research are outlined describing the technical decisions about the system development. The design and implementation of the proposed system are considered including the programs of registration, client database, etc. The testing and evaluation of the system are conducted suggesting recommendations about server applications and limitations.