The main task in this master-thesis is to develop a stable mobile application, which will enable exchange of textual and media content between users in real time (popular name Messenger). To develop this application, the .NET Core will be used for the server part of the application, which will have the role of a web service for manipulating and passing data between users. Angular Javascript framework with a custom Ionic library to create mobile cross-platform applications will be used for the client part of the application. The aim of the master-thesis is primarily the application of these technologies and their functionality working together to create an application that most of us use on a daily basis. As for other technologies to be used (it is currently before the research itself) because of its own the popularity of Google’s Firebase Cloud Messaging is one of the options, but that option will still be explored and the final choice will be explained in the master-thesis. In addition to the approach used, there are also popular, frequently used alternatives such as on the client side React and Vue work environments and Ruby on Rails and some PHP work environments like Laravel or Symphony on the server side. By simply choosing another technology, the architecture itself would probably be the same differed from the one mentioned. Also, in addition to different technology choices, it is possible to choose different ones ancillary services that enable the same type of real-time communication that is practically manual through this application programmed and arranged. Auxiliary services that would allow this have developed their own Rest API services which manage client-side requests and notifications. Examples of code from the application will be in Angular (the client part of the application) while the server part of the application will be in .Net Core.