Fyne — Cross-Platform GUI Toolkit for Go

Introduction

Fyne provides a pure-Go API for building graphical applications that run on Linux, macOS, Windows, iOS, and Android without platform-specific code. It uses OpenGL for rendering, giving a consistent look across all targets while remaining lightweight and fast to compile.

What Fyne Does

• Delivers a material-design-inspired widget set (buttons, lists, trees, forms, tabs)
• Compiles to native binaries for desktop and mobile from Go source
• Renders via OpenGL/ES so UI looks identical across platforms
• Provides a layout system with containers, grids, and responsive sizing
• Includes a CLI tool for packaging, bundling assets, and cross-compiling

Architecture Overview

Fyne separates the API layer (widget tree, canvas, events) from the rendering driver. The default driver uses GLFW for window management and OpenGL for drawing. Widgets are composed declaratively, and the canvas redraws only dirty regions. Mobile targets use gomobile bindings under the hood.

Self-Hosting & Configuration

• Requires Go 1.17+ and a C compiler (gcc) for CGo OpenGL bindings
• On Linux, install dependencies: sudo apt install libgl1-mesa-dev xorg-dev
• Theme customization via fyne.CurrentApp().Settings().SetTheme(myTheme)
• Bundle resources (icons, fonts) using fyne bundle CLI command
• Cross-compile with fyne package -os linux/windows/darwin/android/ios

Key Features

• Single codebase for 5 platforms (Linux, macOS, Windows, iOS, Android)
• Pure Go API with no runtime dependencies beyond OpenGL drivers
• Built-in data binding for reactive UI updates
• Fast compile times leveraging Go's toolchain
• Active widget collection: file dialogs, rich text, split panes, accordions

Comparison with Similar Tools

• Wails — uses web tech (HTML/CSS/JS) for UI; Fyne is pure Go with native rendering
• Gio — also Go-based but uses immediate-mode rendering; Fyne is retained-mode
• Qt (via go-qt) — powerful but heavy C++ dependency and complex CGo bindings
• Electron — cross-platform via Chromium; much larger binary size and memory usage
• Flutter — Dart-based; Fyne keeps everything in the Go ecosystem

FAQ

Q: How large are Fyne binaries? A: Typical desktop apps compile to 10-20 MB. Mobile builds are slightly larger due to bundled assets.

Q: Does Fyne support custom widgets? A: Yes. Implement the fyne.Widget interface with CreateRenderer() to draw custom components.

Q: Can I use Fyne for production mobile apps? A: Yes. Fyne targets iOS and Android, though the mobile widget set is less mature than desktop.

Q: Does it support dark mode? A: Yes. Fyne auto-detects system theme and ships both light and dark built-in themes.

Sources

• https://github.com/fyne-io/fyne
• https://fyne.io