Flutter for Web: Build and Deploy
Flutter for Web compiles your Dart code into a web app. Use `flutter build web` and choose a renderer: HTML for smaller size or CanvasKit for performance. The footgun is the initial download size, which can be large and slow down first-page load.
WHY IT EXISTS: Flutter for Web was created to enable developers to use a single Dart codebase to build applications for mobile, desktop, and the web. This reduces development time and helps maintain a consistent user experience across all platforms without writing a separate web application from scratch.
THE MENTAL MODEL: Think of Flutter for Web not as embedding a mobile app in a browser, but as a compiler that translates your Flutter widgets and logic into standard web technologies. It creates a complete, client-rendered single-page application (SPA) from your existing Dart code, ready to be hosted on any static web server.
HOW IT WORKS: When you run the flutter build web command, the tool compiles your Dart code into JavaScript. It then packages this with a rendering engine and your app's assets into a build/web directory. You must choose a renderer using the --web-renderer flag. The html renderer uses a combination of HTML, CSS, and Canvas elements, resulting in a smaller download size. The canvaskit renderer uses WebAssembly (Wasm) to run the Skia graphics engine directly in the browser, offering higher fidelity and performance that's closer to native mobile, but at the cost of a significantly larger initial download.
WHEN TO USE IT: Use Flutter for Web when you want to deploy an existing Flutter application to a browser, reaching a wider audience without maintaining a separate web codebase. It is ideal for highly interactive applications, internal tools, dashboards, and companion web apps where cross-platform consistency is more important than SEO or the absolute fastest initial load time.
WHEN NOT TO USE IT: Avoid Flutter for Web for content-heavy, static websites that rely on search engine optimization (SEO). As a single-page app, its content is not easily crawlable by search engines. Also, if a minimal initial load time is a critical requirement for a public-facing site, the download size of the Flutter engine and app code can be a significant drawback.
ONE CANONICAL EXAMPLE: To build your app for the web using the high-performance CanvasKit renderer, you run the command: flutter build web --web-renderer canvaskit. This generates a build/web directory containing all the necessary files (index.html, main.dart.js, assets, etc.). You can then deploy this directory to any static web hosting service like Firebase Hosting, Netlify, or GitHub Pages.
Read the original → docs.flutter.dev
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