Bits UI

Bits UI is an open-source headless component library designed specifically for the Svelte ecosystem, providing developers with flexible and accessible primitives for building custom user interface components. Instead of shipping with predefined styles, the library offers unstyled components that focus on behavior and accessibility, allowing developers to fully control the appearance of their UI through their own CSS or design systems. This headless architecture makes Bits UI particularly useful for teams that need reusable UI logic while maintaining consistent branding and visual customization. The project builds on concepts inspired by libraries such as Radix UI and React Spectrum and integrates builder patterns influenced by Melt UI to deliver powerful component abstractions. Developers can use Bits UI to implement complex interface patterns such as dropdowns, modals, and calendars while preserving accessibility standards and predictable interaction behaviors.