📦 stockfish_flutter_plus

A modern, improved Stockfish engine plugin for Flutter — with full Android 16-KB page size support stockfish_flutter_plus is an enhanced and actively maintained fork of the original Stockfish Flutter plugin. It provides a simple and efficient API for running the Stockfish chess engine inside your Flutter applications using FFI.

This version includes:
✔ Updated build configuration
✔ Correct support for Android’s 16 KB memory page size requirement
✔ Automatic NNUE network downloads
✔ Cleaned and improved CMake build
✔ Full compatibility with modern Flutter and Dart SDKs

🚀 Features

🧠 Run Stockfish directly on-device
⚡ Fast evaluation and UCI commands via FFI
📱 Works on Android and iOS
🔧 ARM64 16 KB page support for Google Play compliance
🤝 Simple asynchronous API
🟦 Lightweight, no external dependencies
🔄 Uses the latest Stockfish NNUE networks

Example

@PScottZero was kind enough to create a working chess game using this package, and you can also check out another full implementation created by myself DexterFury.

Usages

iOS project must have IPHONEOS_DEPLOYMENT_TARGET >=12.0.

Add dependency

Update dependencies section inside pubspec.yaml:

  stockfish_flutter_plus: ^1.0.0

Init engine

import 'package:stockfish_flutter_plus/stockfish_flutter_plus.dart';

// create a new instance
final stockfish = Stockfish();

// state is a ValueListenable<StockfishState>
print(stockfish.state.value); # StockfishState.starting

// the engine takes a few moment to start
await Future.delayed(...)
print(stockfish.state.value); # StockfishState.ready

UCI command

Waits until the state is ready before sending commands.

stockfish.stdin = 'isready';
stockfish.stdin = 'go movetime 3000';
stockfish.stdin = 'go infinite';
stockfish.stdin = 'stop';

Engine output is directed to a Stream<String>, add a listener to process results.

stockfish.stdout.listen((line) {
  // do something useful
  print(line);
});

🛠 Android: 16 KB Page Size Support (Important)

Google Play requires modern ARM64 apps to support 16 KB memory pages. This plugin includes updated CMake configurations that compile Stockfish with:

-Wl,-z,max-page-size=16384

This ensures your app passes all Google Play ABI compliance checks. No additional configuration is required from your side.

Dispose / Hot reload

There are two active isolates when Stockfish engine is running. That interferes with Flutter's hot reload feature so you need to dispose it before attempting to reload.

// sends the UCI quit command
stockfish.stdin = 'quit';

// or even easier...
stockfish.dispose();

Note: only one instance can be created at a time. The factory method Stockfish() will return null if it was called when an existing instance is active.

📁 Project Structure

lib/
  stockfish_flutter_plus.dart

android/
  CMakeLists.txt   # Builds Stockfish + 16 KB page size fix
  src/main/cpp/    # FFI Bridge and Stockfish source

ios/
  Stockfish/       # iOS Stockfish source

📦 NNUE Network Handling

On Android, NNUE files are automatically downloaded at build time using:

file(DOWNLOAD ...)

These files are placed into the engine’s working directory and loaded automatically.

🧩 Platform Support

Platform Supported Notes
Android ✅ 16 KB page size compliant
iOS ✅ Fully supported
Windows ❌ Not included in this version
Linux ❌ Not included
Web ❌ Not supported (requires native execution)

📝 License & Attribution

This package is a fork and enhancement of the original plugin: 🔗 https://github.com/ArjanAswal/stockfish The Stockfish engine itself is licensed under the GPLv3, which applies to this package. You must keep your modifications open-source when redistributing.

❤️ Credits

Stockfish engine team: https://stockfishchess.org Original Flutter plugin by Arjan Aswal Improvements and 16 KB support: Raphael (Developer of Stockfish Flutter Plus)

💬 Support

If you have issues, suggestions, or want to contribute: GitHub Issues Pull Requests welcome Contributions appreciated

Libraries

stockfish_flutter_plus