This master's thesis delves into the topic of design creation and handoff processes, with a special emphasis on communication applications. Initially, the paper revisits the basics of design, defining key concepts of User Experience (UX) and User Interface (UI). Particular attention is given to user-centered design (UCD), highlighting the main visual elements of graphic user interfaces (GUI), especially those specific to communication platforms. A pivotal segment of the work focuses on the design handoff document to developers. Here, the importance of communication between designers and developers is analyzed, discussing the optimal content and structure of the document and presenting various tools and techniques that facilitate this process. The practical segment of the paper concerns the actual creation of screens for a communication application. In this part, the author presents the idea for the application, explains the choice of Figma as the primary design tool, conducts market research by analyzing major competitors like Slack, MS Teams, and Rocket Chat, followed by planning and crafting the UX and UI design. In the final phase, the author introduces the concrete creation of the design handoff document. The thesis is substantiated with research, with core hypotheses suggesting that the current design handoff processes to front-end developers often fall short in communication and document transfer, and that a more detailed document with a higher number of elements can facilitate the implementation process for developers.