C++ Lightweight, cross-platform, HTML rendering engine for desktop apps


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Ultralight is a lightweight, cross-platform, HTML rendering engine for desktop apps and games. It supports most modern HTML5 and JavaScript features while still remaining small in binary size and memory usage.

API is available for C and C++, with community bindings for C#, Rust, Java, and Go in our forum here.

Base Memory Usage

Ultralight Electron
Windows 9 MB 72 MB
macOS 17 MB 97 MB
Linux 15 MB 136 MB

Base Distributable Size

Ultralight Electron
Windows 30 MB 147 MB
macOS 43 MB 163 MB
Linux 49 MB 179 MB

Comparison with Chromium

Ultralight Chromium
Renderer Proprietary (GPU) Skia (CPU) / GPU Compositor
Layout Engine WebCore (from WebKit) Blink
JavaScript Engine JavaScriptCore V8
IPC None (Single Process) Yes (Multi Process)

Ultralight is a new port of WebKit combined with a new lightweight renderer intended specifically for embedding in apps and games.

Virtual GPU Renderer

Our optional, high-performance GPU renderer takes advantage of GPU hardware when available. All painting is performed via virtual display lists and translated to your target platform at runtime (see the GPUDriver interface). This renderer is enabled by default when using Ultralight via the AppCore runtime.

Accelerated CPU Renderer

For easier integration into games and environments with limited GPU, Ultralight can also render to an offscreen pixel buffer using an SIMD-accelerated CPU rendering pipeline. Paths, gradients, and patterns in this mode are rasterized using Blend2D’s high-performance JIT compiler.

HTML Renderer For Games

Ultralight is designed to integrate well into existing games and game engines. Developers have complete control over asset loading via the FileSystem interface and have the ability to provide the library a custom, lockable pixel-buffer for each View to render into (eg, for display of HTML in a texture).

For more info about integrating Ultralight into a game, please see: https://docs.ultralig.ht/docs/integrating-with-games

Cross-Platform AppCore Runtime

AppCore is an optional, cross-platform desktop app runtime built on top of Ultralight that handles window creation, native event loops, native graphics drivers (D3D11, D3D12, Metal, OpenGL), and more.

You can use it to build desktop HTML apps in a manner similar to Electron. It’s currently under active development and only supports single-window apps at this writing. A number of planned features (app icons, automatic packager, borderless windows with custom draggable titlebars, etc) are missing but on the way.

For more info about using Ultralight in a desktop app, please see: https://docs.ultralig.ht/docs/writing-your-first-app

Free License

Ultralight is free for non-commercial use and free for commercial use by companies with less than $100K gross annual revenue. For more info see LICENSE.txt

Commercial Licensing and Support

We offer commercial licensing, priority support, and source code. To learn more, please visit our website.

You can get the latest SDK for each platform via the following links:

Getting Pre-Built Binaries for a Specific Commit

Pre-built binares are uploaded to the following S3 buckets every commit:

Click any of the links for an XML listing of available files.


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