GUI Development in Rust:
Overview of Options (egui, Iced, etc.)

Last updated: April 20, 2025

Table of Contents

1. Introduction: The State of Rust GUI

Developing Graphical User Interfaces (GUIs) in Rust is an area of active development and exploration. Unlike languages with long-established, dominant GUI frameworks (like C# with WinForms/WPF/MAUI, Java with Swing/JavaFX, or Python with Qt/Tkinter bindings), the Rust ecosystem offers a variety of approaches and libraries, each with its own strengths, weaknesses, and maturity level.

Choosing the right tool depends heavily on your project's requirements, performance needs, target platforms, and preferred architectural style. This article provides an overview of the main approaches and highlights some of the most popular Rust GUI crates available today.

2. Key Architectural Approaches

Rust GUI libraries generally fall into a few architectural categories:

2.1 Immediate Mode

In immediate mode GUIs (IMGUI), the UI is drawn from scratch every frame. UI elements (like buttons, sliders) are typically created by calling functions directly within the main application loop or update function. The library doesn't retain a persistent representation of the UI structure; state is managed entirely by the application.

  • Pros: Simple API, easy to integrate into game loops or existing applications, often less boilerplate.
  • Cons: Can be less performant for complex static UIs (though often optimized), layout can be trickier as elements are drawn sequentially, state management is entirely manual.
  • Example: egui.

2.2 Retained Mode (Reactive / Elm-like)

In retained mode, the GUI library maintains an internal representation (a tree or graph) of the UI elements. The application updates this representation based on state changes, and the library efficiently redraws only the necessary parts.

Many modern Rust GUI libraries in this category adopt a reactive approach inspired by functional programming, often similar to the Elm Architecture (Model-View-Update):

  • Model/State: The application's data.
  • View: A function that describes the UI based on the current state.
  • Update/Messages: User interactions generate messages, which are processed by an update function to modify the state, triggering a re-render.
  • Pros: Efficient rendering for complex UIs, clear separation of concerns (state, view, update logic), often better for complex layouts and state management.
  • Cons: Can have a steeper learning curve, might involve more boilerplate than immediate mode.
  • Example: Iced, Druid, Slint.

2.3 Web Technologies

This approach uses standard web technologies (HTML, CSS, JavaScript/Wasm) for the UI layer, running inside a web view component provided by the operating system. The Rust code typically runs as a backend process, communicating with the frontend via an Inter-Process Communication (IPC) bridge.

  • Pros: Leverages existing web development skills, vast styling and component libraries available, excellent cross-platform UI consistency.
  • Cons: Larger binary sizes (includes web view runtime), potentially higher resource usage than native approaches, communication overhead between Rust backend and web frontend.
  • Example: Tauri.

2.4 Bindings to Native Toolkits

This approach involves creating Rust wrappers (bindings) around existing, mature GUI toolkits written in other languages (usually C or C++), such as GTK, Qt, or FLTK.

  • Pros: Leverages mature, feature-rich, and platform-native toolkits, often good accessibility support.
  • Cons: Requires dealing with FFI (unsafe code, potential complexities), API might feel less "Rusty", build dependencies can be complex, cross-platform deployment might require shipping toolkit libraries.
  • Example: GTK-rs, FLTK-rs, qt-rs (less active).

3.1 egui (Immediate Mode)

  • Website: egui.rs
  • Approach: Immediate Mode.
  • Key Features: Extremely easy to integrate, simple API, pure Rust, runs natively and on the web (Wasm/WebGL), good for debug UIs, tools, and simple apps. Backend agnostic (integrations available for `winit`, `bevy`, etc.).
  • Considerations: Layout can be tricky for complex UIs due to the immediate nature. Not designed for highly polished, complex application UIs out-of-the-box.

3.2 Iced (Retained / Elm-like)

  • Website: iced.rs (Docs/Book: book.iced.rs)
  • Approach: Retained Mode (Elm-inspired).
  • Key Features: Cross-platform (Windows, macOS, Linux, experimental Web support), data-centered reactive model, type-safe, built-in widgets, custom styling, async command support. Uses `wgpu` for rendering.
  • Considerations: Still pre-1.0 (as of early 2025), API can change, documentation improving but might require exploring examples, can have a steeper learning curve than `egui`.

3.3 Tauri (Web-based)

  • Website: tauri.app
  • Approach: Web Technologies (WebView frontend, Rust backend).
  • Key Features: Build cross-platform desktop apps using any frontend web framework (React, Vue, Svelte, etc.), smaller bundle size and lower resource usage compared to Electron, secure IPC bridge, extensive plugin system, auto-updater.
  • Considerations: Not a pure Rust GUI solution (requires web development skills), performance limited by the web view, less direct access to native UI elements compared to bindings.

3.4 GTK-rs (Bindings)

  • Website: gtk-rs.org
  • Approach: Bindings to the native GTK toolkit (primarily used on Linux, also available on macOS/Windows).
  • Key Features: Provides access to the mature and feature-rich GTK widget set, generates relatively native-looking applications (especially on Linux), strong accessibility support.
  • Considerations: Requires GTK development libraries to be installed, FFI complexity underlies the bindings, API follows GTK's object-oriented style (using macros to bridge with Rust), Windows/macOS support and look-and-feel might be less ideal than on Linux.

3.5 Other Notable Options

  • Slint: (slint.dev) A newer toolkit with its own declarative markup language and Rust API. Supports desktop, web, and embedded. Commercial licenses available for certain uses.
  • Druid: (github.com/linebender/druid) A data-oriented retained-mode framework, currently less actively developed in favor of the experimental Xilem project by the same team.
  • FLTK-rs: (github.com/fltk-rs/fltk-rs) Bindings to the lightweight FLTK toolkit.
  • Bevy UI: (bevyengine.org) While primarily a game engine, Bevy includes a built-in UI system (often used with `bevy_egui`).

4. Choosing a Framework

Consider these factors:

  • Project Complexity: For simple tools or debug overlays, egui is often sufficient. For complex applications with intricate state, Iced or Slint might be better.
  • Target Platforms: Need web support? egui and Iced (experimental) offer it. Need native desktop? Most options work. Embedded? Slint or potentially egui.
  • Team Skills: Do you have web development experience? Tauri could be a fast track. Prefer pure Rust? Look at egui, Iced, Slint.
  • Desired Look & Feel: Need a truly native look? Bindings like GTK-rs might be best (especially on Linux). Want custom styling? Iced, Slint, Tauri offer more flexibility.
  • Maturity & Stability: Bindings leverage mature toolkits. egui and Tauri are widely used. Iced and Slint are actively developed but newer.
  • Performance Needs: Web-based solutions (Tauri) may have higher baseline overhead. Immediate mode (egui) performance depends on redraw complexity. Retained mode (Iced) can be very efficient.

5. Conclusion

The Rust GUI ecosystem is diverse and evolving rapidly. There isn't a single "best" solution, but rather a range of options catering to different needs and philosophies.

egui offers simplicity for immediate-mode needs. Iced provides a reactive, cross-platform approach. Tauri leverages web technologies effectively. Bindings like GTK-rs tap into mature native toolkits. Newer contenders like Slint are also gaining traction.

Evaluate your project requirements carefully, explore the examples provided by each library, and check resources like Are We GUI Yet? to make an informed decision.

6. Additional Resources

Related Articles

External Links