Open source. Open possibilities.

Numl is a deprecated UI design language, web-component library and runtime CSS framework for quickly building interfaces that follow a design system, loadable with a single JavaScript module and no bundler or config.

Happy DOM is a JavaScript implementation of a web browser's DOM without a graphical user interface, designed so browser-style code and component tests can run in runtimes like Node.js and Bun.

CompoMo (@ds-mo/ui) is a framework-agnostic Stencil.js web component library styled with TokoMo design tokens, shipping generated Angular, React and Vue adapters alongside an MCP metadata server.

Media Chrome provides customizable web component controls for audio and video players, compatible with any framework and many media sources.

FAST is Microsoft's adaptive interface system for the modern web, providing a lightweight framework for building standards-compliant Web Components plus a Fluent design component library.

Material Web (@material/web) is a library of web components implementing Google's Material 3 design system, for building accessible web apps. It ships from npm and can be loaded directly from a CDN. Note: the project is in maintenance mode pending new maintainers.

AgnosticUI Local (v2) is a CLI-based, framework-agnostic UI component library that copies component source, styles and tests directly into your project for React, Vue, Svelte or Lit, with 55 accessible components, CSS custom-property theming and AI prompt playbooks.

Chroma Chords is a tactile web audio widget for quickly generating and arranging chord progressions by vibe, genre, and mood, with theory analysis and MIDI/WAV export.

Official LottieFiles web player for Lottie (.json) and dotLottie (.lottie) animations, with a Rust + WASM core, Canvas2D/WebGL2/WebGPU backends, runtime theming, state machines, audio, worker rendering, and React, Vue, Svelte, Solid and Web Component SDKs.

Storybook is a frontend workshop for building, documenting, and testing UI components and pages in isolation. It supports many frameworks and offers addons for accessibility, documentation, and interactive development.