Tabletop exercises at the INJECT Exercise Platform are defined in the YAML format and prepared using standard text editors or integrated development environments. The goal of this thesis is to create a web application that will guide the exercise designers a make the whole process more effective. 
The application will enable the preparation of the exercise and its components without knowledge of YAML formatting and relations between individual YAML files. The editor will be a stand-alone application in the React framework but ready to be integrated with the INJECT Exercise Platform. The student will test its purpose and usability by recreating existing exercise definitions. The lessons learned and limitations will be reported in the thesis text.