Digital Twin (DT) refers to a digital representation of a physical entity and its functions, behaviors and rules. Digital Twin (DT) technology, originally, emerges from manufacturing and aerospace sectors. With the advancement of Industry 4.0 and IoT, DT is applied in other domains like cyber-physical systems (CPS), building, and health. This scattering of the DT technology results in a lack of clear and concise definition of what is exactly a DT.In this context, we want to explore what could be a DT for Software Applications (SA). This paper describes the approach that we will follow to identify what could be a DT for Software Applications. On the basis of the features (of a DT) identified in the other domains, we propose ways to define a DT for Software Applications. In a first approach, we propose to use structural and behavioral UML diagrams to instrument the application (by defining software probes), and we visualize the results in a "dashboard". This gives us the "monitoring" features of the DT. From this approach, we want to explore the other features (simulation, prediction, optimization…) that will allow us to propose a more complete digital twin.