Flutter Code Obfuscation

What is Obfuscation?

Replaces function/class names with obscure symbols to make reverse engineering harder.

Warning: Obfuscation only renames symbols - it does NOT encrypt resources or provide strong security. Never store secrets in the app.

Supported Platforms

Platform	Build Targets
Android	`aar`, `apk`, `appbundle`
iOS	`ios`, `ios-framework`, `ipa`
Desktop	`linux`, `macos`, `macos-framework`, `windows`
Web	Not supported (uses minification instead)

Build with Obfuscation

Basic Command

bash

flutter build <target> \
  --obfuscate \
  --split-debug-info=<symbols-directory>

Examples

bash

# Android APK
flutter build apk --obfuscate --split-debug-info=out/android

# Android App Bundle
flutter build appbundle --obfuscate --split-debug-info=out/android

# iOS
flutter build ios --obfuscate --split-debug-info=out/ios

# iOS IPA
flutter build ipa --obfuscate --split-debug-info=out/ios

# macOS
flutter build macos --obfuscate --split-debug-info=out/macos

# Windows
flutter build windows --obfuscate --split-debug-info=out/windows

# Linux
flutter build linux --obfuscate --split-debug-info=out/linux

Important: Backup the generated symbol files!

Symbol Files

Generated in <symbols-directory>:

code

out/android/
├── app.android-arm.symbols
├── app.android-arm64.symbols
└── app.android-x64.symbols

Always backup these files - required for crash report deobfuscation.

Deobfuscate Stack Traces

Command

bash

flutter symbolize -i <stack-trace-file> -d <symbols-file>

Example

bash

# Save crash stack trace to file
echo "crash stack trace content" > crash.txt

# Deobfuscate
flutter symbolize -i crash.txt -d out/android/app.android-arm64.symbols

Generate Obfuscation Map

Creates JSON mapping of original → obfuscated names:

bash

flutter build apk \
  --obfuscate \
  --split-debug-info=out/android \
  --extra-gen-snapshot-options=--save-obfuscation-map=out/android/map.json

Output (map.json):

json

["MaterialApp", "ex", "Scaffold", "ey", "MyWidget", "ez", ...]

Limitations

Code That Will Break

dart

// BAD: Runtime type checking fails after obfuscation
expect(foo.runtimeType.toString(), equals('Foo')); // ❌

// BAD: Type name comparison
if (widget.runtimeType.toString() == 'MyWidget') { } // ❌

What's NOT Obfuscated

•Enum names (remain unchanged)
•String literals
•Asset paths

Quick Reference

Task	Command
Build obfuscated APK	`flutter build apk --obfuscate --split-debug-info=out/android`
Build obfuscated IPA	`flutter build ipa --obfuscate --split-debug-info=out/ios`
Deobfuscate crash	`flutter symbolize -i crash.txt -d app.android-arm64.symbols`
Generate map	Add `--extra-gen-snapshot-options=--save-obfuscation-map=map.json`
Check options	`flutter build <target> -h`

Workflow Summary

code

1. Build with --obfuscate --split-debug-info=<dir>
2. Backup symbol files (*.symbols)
3. Distribute obfuscated app
4. When crash occurs: flutter symbolize -i <crash> -d <symbols>

Official Docs

•Obfuscate Dart code