This article discusses the challenges and solutions for implementing authentication flows in Flutter applications across both mobile and web platforms. While Flutter initially focused on mobile development, the expansion to web and desktop platforms has introduced complexities, particularly in authentication processes. On mobile, developers can reliably control user access to authenticated pages, but on the web, users can manipulate browser navigation to access protected content. The article illustrates these differences with a dashboard example and proposes using route guards to manage authentication more effectively. By leveraging tools like Flutter's `auto_route`, developers can automate route generation and implement route guards, ensuring secure navigation across platforms. The piece highlights that route guarding on Flutter web can also be applied to mobile, facilitating a more unified approach to multi-platform development.