Web and mobile applications consist of real-time events of different kinds in order to ensure the best possible user experience. To develop such applications, proper tools are needed and reactive programming is one of the possible solutions. Due to its many advantages, reactive programming is becoming an increasing reason to abandon standard object-oriented approach. Therefore, in this thesis we first describe the concepts of reactive programming and compare it to object-oriented programming. We continue by comparing numerous available frameworks for developing reactive applications. Framework Vert.x is described in more detail. Main contribution of this thesis is implementation of Vert.x in the open-source framework KumuluzEE which is used to develop microservices.