Flutter 3.35 Web Hot Reload: Faster Iteration in the Browser

Introduction

Flutter 3.35, released on August 13, 2025, marks a major milestone for Flutter Web by enabling stateful hot reload by default—no experimental flags required. This unlocks significantly faster browser-based development with seamless iterations and persistent app state. In the sections below, you'll learn how to leverage it effectively and why it's such a productivity booster.

Stateful Hot Reload on Web (Enabled by Default)

Flutter 3.35 brings stateful hot reload on the web out of the box. Previously, this required the --web-experimental-hot-reload flag. Now, any Flutter web app in debug mode allows you to modify UI or logic and see the changes instantly—without losing your app’s state. :contentReference[oaicite:0]{index=0}

What Changed

• Old workflow (pre-3.35): Required flags like --web-experimental-hot-reload; without them, you'd lose UI state or need a full page refresh.

• New workflow: Run your app normally in debug. Changes are injected live, and the app state persists—even deep in the navigation stack.

Other Noteworthy Features in Flutter 3.35

Beyond hot reload, this release brings several developer-friendly enhancements:

WASM Dry Runs

Dart/Web now performs a two-phase build: standard JavaScript plus a WebAssembly (Wasm) dry run, producing console warnings for Wasm-readiness. This paves the way for smoother future Wasm adoption.

Accessibility & Semantics Polish

Flutter 3.35 improves accessibility with:

• Richer web semantics and locale-aware behaviors (e.g., SemanticsLabelBuilder and SliverEnsureSemantics)

• Better VoiceOver and TalkBack support for Cupertino and Android components

Widget Previews & Tooling

The experimental Widget Previews feature gains support for themes, localization, and pub workspaces, enhancing dev-time visualization workflows.

Performance and UI Enhancements Across Platforms

• Improved sliver painting control and Impeller performance under the hood.

• Updated Material widgets: M3 RangeSlider, DropdownMenuFormField, scrollable NavigationRail.

• Raised minimum OS versions: iOS 13, Android SDK 24, macOS 10.15 and UI/Platform thread merging for better desktop resizing.

How to Take Advantage of Web Hot Reload

1. Upgrade your Flutter SDK: Ensure you're on Flutter 3.35 (released August 13, 2025).

2. Run your web app in debug mode (e.g., flutter run -d chrome). No flags needed.

3. Edit your Dart files and use the hot reload trigger (e.g., r in terminal or IDE button).

4. Confirm: UI updates appear instantly, and state (e.g., form input, navigation) remains—the hallmark of true stateful hot reload.

Why It Matters for Mobile-Web Workflows

• Speeds up dev cycles: No need for full page refreshes—just edit, save, see the result.

• Preserves app context: Deep edits won’t reset login or navigation state, so you can iterate faster on production edges.

• Consistent experience across platforms: Matches hot reload behavior on iOS, Android, and desktop—making dev habits easier to maintain.

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Conclusion

Flutter 3.35 elevates web development by integrating stateful hot reload seamlessly—no more flags or cumbersome resets. Combine that with enhanced accessibility, theme-aware previews, and performance tools, and you’ve got a more fluid, powerful Flutter web dev experience.