Nuklear

Nuklear is a small, cross-platform immediate-mode GUI toolkit written in ANSI C. It is designed to be embedded in applications and games, offering a compact API and a minimal runtime footprint. The library is backend-agnostic: UI state and widgets are defined in code, while rendering is performed by the host application using a rendering backend of its choice. Nuklear provides integration samples for common graphics APIs and window toolkits, including OpenGL, Direct3D, Vulkan, and backends for SDL and GLFW.

The architecture centers on a context that holds the UI state. Developers compose interfaces by creating windows and widgets such as buttons, checkboxes, sliders, text inputs, radio buttons, combo boxes, color editors, progress bars, and simple charts. The library handles layout decisions within the immediate-mode paradigm, returning widget states on each frame. Styling is supported via a straightforward style system, allowing themes and color customization.

Nuklear originated as a compact GUI solution for C projects and has been used in game tooling, editors, and embedded interfaces where a lightweight UI layer is advantageous. It is often contrasted with newer, larger immediate-mode GUI libraries, offering a smaller footprint and a simpler API at the cost of fewer built-in conveniences. The project relies on community-maintained backends and samples to integrate with various platforms and rendering stacks.

Notes and scope: Nuklear emphasizes speed and simplicity over feature richness. Its backends require manual integration for rendering, and it is best suited for applications that need a lightweight, embeddable UI without heavy dependencies or a large runtime.