The increasing proliferation of drones, or Unmanned Aircraft Systems (UAS), has opened new opportunities for monitoring, surveillance, and other industrial and civil applications. However, flight mission planning in these contexts presents significant challenges, particularly in terms of safety, risk management, and regulatory compliance. Conducting flight operations in populated environments poses risks to people on the ground: a potential incident resulting in the drone crashing could harm individuals, potentially leading to casualties. Consequently, developing tools for risk assessment and safe route planning is crucial to enable the use of drones in urban environments. In this thesis, an interactive web application is developed for the safe planning of drone flight operations in populated environments, aiming to provide a practical and secure tool for professional users, such as drone operators or surveillance agencies.