Multimedia Group developed the mobile app for iOS for the TEDxThessaloniki event. The application is available for free on iTunes. The app was implemented in the context of SocialSensor in the process of gathering realistic user requirements and feedback for various types of events. Also for testing implementation technologies and approaches towards gathering significant experience for the SocialSensor use case prototypes. TEDx Thessaloniki event offered a unique opportunity since it attracts a large audience familiar with mobile apps and social media usage.