flutter-reducing-app-size

SKILL.md

Measure and optimize Flutter app bundle size across platforms with analysis tools and reduction strategies.

Generates detailed size analysis JSON files via --analyze-size flag to identify large packages, libraries, and assets contributing to bloat

Visualize and compare builds using DevTools app size tool with treemap inspection and diff functionality to track optimization progress

Supports Android (APK/AAB), iOS, and desktop platforms with platform-specific workflows, including iOS app thinning size estimation via Xcode

Implements four core reduction strategies: debug symbol splitting, unused resource removal, library resource minimization, and media compression

Reducing Flutter App Size

Contents

Core Concepts

Workflow: Generating Size Analysis Files

Workflow: Analyzing Size Data in DevTools

Workflow: Estimating iOS Download Size

Workflow: Implementing Size Reduction Strategies

Examples

Core Concepts

Debug vs. Release: Never use debug builds to measure app size. Debug builds include VM overhead and lack Ahead-Of-Time (AOT) compilation and tree-shaking.

Upload vs. Download Size: The size of an upload package (APK, AAB, IPA) does not represent the end-user download size. App stores filter redundant native library architectures and asset densities based on the target device.

AOT Tree-Shaking: The Dart AOT compiler automatically removes unused or unreachable code in profile and release modes.

Size Analysis JSON: The --analyze-size flag generates a *-code-size-analysis_*.json file detailing the byte size of packages, libraries, classes, and functions.

Workflow: Generating Size Analysis Files

Use this workflow to generate the raw data required for size analysis.