Building a large-scale Flutter mobile banking application with 25 Flutter Devs and 200 other team members has taught us many valuable lessons on how to set up such a project. We would like to give you our perspective on the organization of the project and challenges such as code ownership, communication, and design system, which are vital to ensure high productivity while keeping the team happy. At the end, we'd like to share our challenges that we have with our large user base and what main obstacles we had to cope with during the first year after initial production release.