In software development, a lack of collaboration between security experts and software engineers can result in vulnerabilities and weaknesses in software systems. This can lead to severe consequences such as data breaches, system crashes, and financial losses. Even threat modeling often lack detailed procedures and reference models for brainstorming sessions, making them sub-optimal and requiring significant effort. Therefore, a collaborative security-by-design platform is needed to actively involve all participants from the beginning, providing guidance and formalized processes for threat modeling to develop more secure and reliable software systems.