Are you an experienced mobile developer looking for a challenging project?At Sii, we’re collaborating with a leader in cloud communication technology, known for revolutionizing the telecommunications industry. We’re seeking a talented Flutter Developer to join our team and contribute to building innovative solutions for voice, video, and messaging applications. This is your chance to work on a cutting-edge project and grow with industry experts.Your tasks Developing and implementing core features using Flutter, with a focus on integrating native Android/iOS components when necessary, depending on the project’s requirements Building custom OAuth 2.0 clients and ensuring secure authentication flows, maintaining high standards of security and scalability Implementing WebRTC for real-time voice communication, utilizing Flutter plugins, WebSockets, and possibly native solutions for optimal performance across iOS and Android platforms Designing and developing user interface components with Flutter, aiming for an intuitive and polished user experience Integrating CRM systems to ensure smooth data synchronization and communication between the mobile application and backend services Requirements 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 Polish required Residing in Poland required What we offer  Great Place to Work since 2015 - it’s thanks to feedback from our workers that we get this special title and constantly implement new ideas  Employment stability - revenue of PLN 2.1BN, no debts, since 2006 on the market  We share the profit with Workers - over PLN 76M has already been allocated for this aim since 2022  Attractive benefits package - private healthcare, benefits cafeteria platform, car discounts and more  Comfortable workplace – class A offices or remote work  Dozens of fascinating projects for prestigious brands from all over the world  PLN 1 000 000 per year for your ideas - with this amount, we support the passions and voluntary actions of our workers  Investment in your growth – meetups, webinars, training platform and technology blog – you choose  Fantastic atmosphere created by all Sii Power People  If you’re ready to take on this exciting opportunity, apply now!