Single Page WebApp (SPA) has existed for nearly 2 decades, and it was always been built with JavaScript + HTML + CSS. Meanwhile, WebAssembly has provided another way to build web apps that compile other languages to support web apps. This presentation walks you through building Flutter WebApps using WebAssembly, with a deep dive into how Dart languages and Garbage collection is used in Flutter to support Wasm, provided with code examples and performance comparison. Then it goes on to provide information on web app deployment on the GCP platform, focusing mostly on Firebase and Cloud Run.