At least 5 years of experience as a mobile developer, with a strong background in Flutter and native mobile development (either Android or iOS), Solid experience in either native Android development or native iOS development, combined with expertise in Flutter for cross-platform app development, Proficiency in OAuth 2.0, including the ability to implement secure authentication mechanisms in mobile applications, Experience with WebRTC or SIP for real-time communication, as well as familiarity with WebSockets for building scalable and high-performance applications, Very good command of English – min. B2 level, Fluent in Polish required, Residing in Poland required