Choosing the right UI framework is crucial for modern software development, as it impacts performance, development speed, and long-term maintainability. Whether building embedded systems, mobile apps, or cross-platform applications, developers must consider factors like performance, flexibility, ease of use, and ecosystem support.
In this article, we compare Qt, Slint, Flutter, React Native, and Unreal Slate UI—highlighting their strengths, weaknesses, and best use cases.
Overview of the UI Frameworks
| Framework | Language | Platforms | Best For | Rendering Engine |
|---|---|---|---|---|
| Qt | C++ & QML | Embedded, MCU, Desktop, Mobile | Complex UIs, performance-critical apps, cross-platform UIs | Qt Quick (Scene Graph) |
| Slint | Rust & Slint | Embedded, MCU, Desktop, Mobile | Lightweight UI, memory-efficient devices, cross-platform UIs | Qt Renderer/Software Renderer/FemtoVG Renderer/Skia Renderer |
| Flutter | Dart | Mobile (iOS, Android), Desktop, Web, Embedded | Custom UI, animations, startups | Impeller/Skia (on Web) |
| React Native | JavaScript/TypeScript | Mobile (iOS, Android), Desktop, Web, Embedded (limited) | Web-to-mobile apps, fast iteration | Fabric |
| Unreal Slate UI | C++ | All Unreal Engine 4 supported platforms/Mobile/Desktop/Embedded | High-performance embedded UI with 3D capabilities | Unreal Engine 4 (UE4) Rendering Hardware Interface (RHI) |
Qt: A Mature & Versatile UI Framework
✅ Strengths
- Cross-platform: Runs on embedded, MCUs, desktop, and mobile.
- High-performance: Uses C++ for native speed.
- QML for UI Design: Declarative syntax for UI and animations.
- Rich ecosystem: Provides Qt Quick Controls, networking, 3D rendering, and more.
❌ Limitations
- Learning curve: Requires C++ expertise for advanced functionality.
- Licensing: Open-source version available; commercial licensing may be required for enterprise use or specific Qt modules.
Best Use Cases
- Automotive dashboards (e.g., Mercedes-Benz MBUX)
- Industrial HMI and medical devices
- Desktop applications with modern UI
Slint: Lightweight UI for Embedded Systems
✅ Strengths
- Ultra-lightweight: Minimal RAM and CPU usage.
- Rust integration: Safe, memory-efficient programming.
- Declarative UI: Similar to QML but with a simpler syntax.
- No runtime dependencies: Smaller binaries, faster startup times, lower memory usage.
- Flexible open-source and affordable commercial licensing for every use case.
❌ Limitations
- Less mature: Still growing compared to Qt.
- Limited tooling: Core features like live preview are available, but less advanced than full IDEs like Qt Creator.
Best Use Cases
- Memory-constrained embedded/MCU devices (wearables, IoT panels).
- Automotive instrument clusters.
- Simple yet high-performance UIs.
Flutter: Custom UI with High Performance
✅ Strengths
- Full control over UI rendering with Impeller/Skia.
- Works on Mobile, Desktop, Web & Embedded.
- Rich animation and custom UI design.
- Hot Reload for fast UI testing.
❌ Limitations
- Uses Dart, which has a smaller ecosystem.
- Larger app size compared to native.
- Not ideal for real-time low-latency applications.
Best Use Cases
- Beautiful & animated mobile UIs.
- Startups & MVPs needing fast iteration.
- Apps requiring consistent design across platforms.
React Native: Bridging Web & Mobile Development
✅ Strengths
- Single JavaScript codebase for iOS & Android.
- Native UI components for smooth UX.
- Large developer community.
- Fast iteration via Hot Reload.
❌ Limitations
- Performance overhead due to JavaScript bridge.
- Limited embedded/desktop support.
- Complex animations require workarounds.
Best Use Cases
- Web developers moving to mobile.
- E-commerce apps, social media apps.
- Cross-platform mobile solutions.
Unreal Slate UI: A New Embedded UI Concept
✅ Strengths
- 3D UI rendering capabilities.
- C++ integration for high performance.
- Works well in real-time environments.
- Potential for next-gen automotive UIs.
❌ Limitations
- Early-stage adoption for embedded.
- More suited for gaming interfaces.
- Requires Unreal Engine integration.
Best Use Cases
- Futuristic embedded UIs (AR/VR automotive displays).
- Interactive kiosks with real-time elements.
- High-end HMI applications.
Which UI Framework Should You Choose?
| Use Case | Best Framework |
|---|---|
| Automotive & Embedded UI | Qt, Slint, Unreal Slate UI |
| Mobile Applications | Flutter, React Native |
| High-Performance 3D UI | Unreal Slate UI |
| Memory-Constrained Embedded Devices | Slint |
Each UI framework has its unique strengths depending on the project needs. Qt offers a complete cross-platform solution, Slint is a rising star in embedded, Flutter & React Native dominate mobile, and Unreal Slate UI is an interesting new player in embedded UIs.
Choosing the right framework depends on performance needs, platform support, and development workflow.