Run Go inside Flutter

Flap

Flap is a template project that enables seamless integration of Go code into Flutter applications. It allows you to compile Go code directly into your Flutter app, providing high-performance native functionality across multiple platforms.

Features

• Cross-platform support: Web, Android, and iOS
• RPC communication: Bidirectional RPC between Dart and Go
• Push notifications: One-way push messages from Go to Dart
• Protocol Buffers: Efficient serialization with protobuf
• SQLite integration: Built-in SQLite support for data persistence
• WebAssembly: Web platform support via TinyGo and WebAssembly

Supported Platforms

• 🌐 Web (using TinyGo and WebAssembly)
• 🤖 Android
• 🍎 iOS

Quick Start

Using the CLI (Recommended)

1. Install the Flap CLI:

   brew install nosuta/flap/flap

2. Create a new project:

   flap

   This will check dependencies, prompt for your app name and bundle ID, clone the template, and run the full setup automatically.

Manual Setup

Prerequisites

• Go 1.25.0 or later
• Flutter 3.10.0 or later
• Protocol Buffers compiler (protoc)
• Perl
• npm (for Web development)
• TinyGo (for Web platform)
• Chrome (for Web testing)

Setup Steps

1. Clone this repository:

   git clone https://github.com/nosuta/flap.git
   cd flap

2. Create custom configuration:

   cp template.mk custom.mk

   Edit custom.mk to fill in your environment variables.

3. Prepare the project:

   make prepare

4. For Web development, prepare WebAssembly testing:

   make prepare_go_wasm_test

Usage

Running the App

Run on different platforms:

# Web
make web_run

See all available commands:

make help

Defining RPC Services

Flap uses Protocol Buffers to define RPC services between Dart and Go. The code generators use service name suffixes to determine what code to emit.

Standard RPC (Dart → Go → Dart)

Services ending with Service generate standard RPC clients:

service NostrService {
  rpc FetchNotes(NotesRequest) returns (stream Note);
}

Side	Generated Code
Dart	NostrRpcClient — Call Go from Dart
Go	NostrRPCHandler interface + HandleNostrRPC() router

Reverse RPC (Go → Dart → Go)

Services ending with ReverseService generate reverse RPC where Go calls Dart:

service NostrReverseService {
  rpc Nip07SignEvent(Nip07SignEventRequest) returns (Nip07SignEventResponse);
}

Side	Generated Code
Dart	NostrReverseRpc abstract class — Extend and implement methods
Go	NostrReverseRPCNip07SignEvent(ctx, req) caller function

Push Messages (Go → Dart)

Messages starting with Push are one-way notifications:

message PushNip05 { ... }

Side	Generated Code
Dart	PushHandler — Typed streams per message type
Go	SendPushNip05(msg) pusher function

Development

Updating from Template

If you started from this template, you can pull in updates:

git fetch upstream
git merge upstream/master

Acknowledgements

At the early stage of this project, it was heavily influenced by flutter-openpgp, which convinced me of the potential of the Go–Flutter bridge.