Kael

A high-performance, GPU-accelerated UI framework for building native desktop applications in Rust.

Built on top of GPUI from Zed Industries, extended with webviews, media playback, system tray, form controls, rich text, Lottie animations, blur effects, gesture recognition, theming, and more.

Kael targets macOS, Linux, and Windows with platform-native rendering backends (Metal, Vulkan/Blade, DirectX 11) and delivers 60fps with minimal CPU usage through dirty tracking and render-on-demand.

Features

Rendering & Graphics

• GPU-accelerated rendering with per-platform shaders
• Cached surface rendering with dirty tracking (idle at 0% CPU)
• Canvas drawing API with stroked/filled paths, shapes, transforms
• Backdrop blur and frosted glass effects
• Lottie animation playback with background frame rendering
• SVG rendering and icon atlas system
• Device-pixel snapping for crisp output at any DPI

Layout & Elements

• Flexbox and grid layout (via Taffy)
• Rich text with inline elements, entities, and selection
• Recycling lists for heterogeneous content
• Uniform lists for same-height items
• Implicit style transitions (opacity, scale, background, border)
• Explicit keyframe and spring animations
• Elastic (rubber-band) scrolling
• Gesture recognizers (pan, swipe, pinch)
• Form controls: text input, checkbox, toggle, slider, radio, select, date picker

Platform Integration

• System tray with menus
• Global hotkeys
• Native file/save dialogs
• Notifications
• Printing
• WebViews (macOS WKWebView, Windows WebView2, Linux WebKitGTK via wry)
• Media playback (audio/video)
• Screen and media capture
• Overlay and click-through windows
• Auto-launch, single instance, dock control
• Biometric authentication
• Power-aware rendering (battery detection, animation throttling)

Architecture

• Entity-based reactive state management
• Multi-window support
• In-window layer stack (modals, popovers, anchored layers)
• Focus management and keyboard navigation
• Action dispatch system with keybindings
• Theme system with hot-reload from TOML/JSON
• Extension host with WASM sandboxing
• Process isolation (worker children, extension children)
• IPC transport layer
• Session persistence

Quick Start

Add to your Cargo.toml:

[dependencies]
kael = { git = "https://github.com/Augani/kael" }

use kael::*;

struct Counter {
    count: i32,
}

impl Render for Counter {
    fn render(&mut self, _window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
        div()
            .flex()
            .flex_col()
            .gap_2()
            .child(format!("Count: {}", self.count))
            .child(
                div()
                    .cursor_pointer()
                    .child("Increment")
                    .on_click(cx.listener(|this, _, _, _| {
                        this.count += 1;
                    })),
            )
    }
}

fn main() {
    Application::new().run(|cx| {
        cx.open_window(WindowOptions::default(), |_, cx| {
            cx.new(|_| Counter { count: 0 })
        })
        .unwrap();
    });
}

Examples

cargo run -p kael --example hello_world
cargo run -p kael --example animation
cargo run -p kael --example recycling_list
cargo run -p kael --example webview_demo
cargo run -p kael --example daemon_app
cargo run -p kael --example form_controls
cargo run -p kael --example platform_features

Platform Support

Platform	Renderer	Status
macOS	Metal	Full support
Linux (X11)	Blade (Vulkan)	Full support
Linux (Wayland)	Blade (Vulkan)	Full support
Windows	DirectX 11	Full support

Project Structure

crates/
├── kael/           # Core framework
├── kael-macros/    # Proc macros (derive Render, Action, etc.)
├── kael-media/     # Media playback integration
├── collections/    # Optimized collection types
├── refineable/     # Style refinement system
├── util/           # Shared utilities
└── ...

Building

# Check
cargo check -p kael

# Run tests
cargo test -p kael

# Run an example
cargo run -p kael --example hello_world

Linux Dependencies

# Ubuntu/Debian
sudo apt install libwayland-dev libxkbcommon-dev libvulkan-dev \
  libwebkit2gtk-4.1-dev libgtk-3-dev libdbus-1-dev libnotify-dev

# Fedora
sudo dnf install wayland-devel libxkbcommon-devel vulkan-loader-devel \
  webkit2gtk4.1-devel gtk3-devel dbus-devel libnotify-devel

Acknowledgements

Kael is built on GPUI, the UI framework created by Zed Industries for the Zed code editor. The original GPUI code is licensed under Apache-2.0.

License

Apache-2.0 — see LICENSE for details.

Original GPUI code: Copyright 2022-2025 Zed Industries, Inc.