Open-source alternatives to Stencil

Fluent UI is a design system framework and TypeScript UI toolkit providing a comprehensive set of styles and accessibility guidelines. It functions as a React UI component library and a web component library, offering a collection of pre-styled elements and layout utilities to create a cohesive visual experience across web platforms. The project translates a brand design language into a functional library of reusable components, ensuring cross-product visual consistency. It enables the implementation of design systems for enterprise web applications through the use of standardized visual and

Material UI is a comprehensive component-based library designed to accelerate the construction of professional, accessible web interfaces. It provides a centralized design system framework that manages visual tokens, typography, and color palettes to ensure consistent branding and layout constraints across complex application architectures. By encapsulating behavioral and accessibility logic within modular primitives, the library enables developers to build inclusive user experiences that adhere to rigorous design standards. The project distinguishes itself through a zero-runtime styling engi

Solid is a declarative JavaScript framework for building user interfaces through fine-grained reactivity. By utilizing a compile-time template transformation process, it converts JSX into direct DOM manipulation instructions, eliminating the need for a virtual tree. This architecture allows the framework to track dependencies at the individual element level, ensuring that state changes trigger surgical updates to the interface. The framework distinguishes itself through its isomorphic rendering pipeline, which shares reactive logic across server and client environments to support both initial

Mitosis is a cross-framework compiler that transforms a single JSX-based source into native components for multiple frontend libraries simultaneously. It functions as a multi-target UI library builder, allowing developers to maintain a single source of truth for design systems while generating production-ready code for diverse environments including React, Vue, Angular, and Svelte. The system operates by parsing unified component code into an intermediate JSON representation, which serves as the foundation for all downstream framework generators. This architecture utilizes a visitor-based tra

Taiga UI is an Angular UI component library and accessible design system used for building enterprise web interfaces. It provides a comprehensive collection of reusable interface elements and layout tools, functioning as a mobile-first UI kit with responsive components that adapt to different device capabilities. The library distinguishes itself through an integrated data visualization library featuring various chart types and a dedicated form management framework with built-in validation and formatting for specialized data. It also features AI-driven development workflows by integrating comp

Material Web is a framework-agnostic library of reusable user interface components built on native browser standards. It provides a collection of interactive elements that follow official design system specifications, enabling the creation of consistent and accessible interfaces across diverse web applications. The library utilizes custom elements and shadow DOM to ensure style encapsulation and component logic isolation. By leveraging native browser APIs, it maintains design integrity and functional consistency across all major web browsers and varying screen sizes. The project supports ent

uni-app is a cross-platform framework for building mobile and web applications from a single Vue.js codebase. It provides a multi-platform app compiler and a cross-platform UI library to ensure consistent behavior and visual presentation across different operating systems. The project features a native API bridge and a universal plugin system that wrap native SDKs into a unified interface, allowing developers to access device hardware and operating system functions. It utilizes a specialized rendering engine and native performance compilation to bypass standard document overhead and achieve h

This project is a technical reference and guide for optimizing the performance of Angular applications. It provides a comprehensive checklist for improving speed and efficiency by focusing on bundle optimization, rendering best practices, and runtime execution. The guide covers a wide array of differentiators including the implementation of progressive web app strategies through service workers and offline caching. It also details methods for improving perceived load times using server-side rendering and application shells. The repository provides guidance on broader capability areas such as

This project is a design system toolkit and component library that provides a framework-agnostic approach to building web interfaces. It centers on an HTML-first development model, utilizing standard markup and utility-based CSS classes to construct consistent, responsive layouts. The library is built upon the UIkit 3 framework, allowing for the integration of pre-styled interface elements while maintaining control over the underlying markup structure. It further extends these capabilities through web component encapsulation, using custom elements to provide modular and isolated interface log

FAST is a web components framework and declarative UI library used to build adaptive user interfaces. It functions as a server-side rendering engine and design system implementation, enabling the creation of modular components based on web standards. The framework focuses on cross-framework component compatibility, allowing user interface elements to remain functional across different front-end frameworks and modern browsers. It implements a design language through a collection of pre-defined visual components to ensure consistency across professional applications. The system covers state-dr

Kemal is a high-performance web framework for the Crystal language, designed for building scalable APIs and web applications. It provides a natively compiled web server environment that leverages ahead-of-time compilation to maximize request speed and minimize memory overhead. The framework is distinguished by a middleware-based routing engine that uses pattern-matching and a chainable pipeline for flexible request filtering. It includes a dedicated server-side template engine for generating dynamic HTML and a WebSocket communication server for bidirectional real-time messaging and state broa

Quark Design is a library of reusable interface components built on browser-native web standards. By utilizing custom elements and shadow DOM encapsulation, the project provides a suite of UI elements that function as native browser objects, ensuring consistent visual rendering and behavior across diverse environments. The library is designed to be framework-agnostic, allowing components to be integrated into any web project as standard HTML tags. Because it operates on native browser primitives rather than relying on virtual DOM reconciliation, it maintains a lightweight runtime execution mo

Ariakit is a headless component library and accessible UI component toolkit. It provides a set of unstyled web components with built-in accessibility patterns to ensure that screen readers and keyboard navigation function correctly. The project includes an adaptive color engine that calculates high-contrast text and dynamic surface colors for light and dark modes. It also features a concentric layout engine for computing nested padding, margins, and border radii for circular interface elements, alongside a design token system for managing global CSS variables. The toolkit covers broad capabi

Mithril.js is a JavaScript UI framework designed for building single page applications. It functions as a virtual DOM library and a toolkit for creating dynamic user interfaces that synchronize application state with the browser display. The project integrates a client side router for mapping URLs to specific views and a built-in XHR data fetcher for sending and receiving information from servers. These components allow for navigation and content updates without requiring full page reloads. The framework covers user interface state management and asynchronous data fetching, utilizing virtual

Vue is a progressive, component-based JavaScript framework designed for building reactive user interfaces and single-page applications. It centers on a declarative template system that transforms HTML into efficient render functions, allowing developers to organize complex interfaces into isolated, reusable units that synchronize automatically with application state. The framework distinguishes itself through a dependency-tracking reactivity system that monitors data access during rendering to trigger precise updates. It provides a flexible architecture that supports both incremental adoption

React is a JavaScript library for building user interfaces based on a component-driven architecture and unidirectional data flow.

Leptos is a full-stack Rust web framework designed for building reactive applications that share logic and types between the server and the browser. It provides a comprehensive toolkit for developing web interfaces where specific DOM nodes update automatically in response to changes in underlying reactive signals, rather than re-rendering entire component trees. The framework distinguishes itself through a fine-grained reactivity model that tracks dependencies at the individual data point level. It utilizes compile-time template transformation to convert declarative HTML-like syntax into opti

Coss is an accessible UI component library and design system framework used to build web interfaces. It provides a comprehensive kit of interactive elements and layout building blocks that follow screen reader and keyboard navigation standards. The project functions as a UI overlay management library, offering specialized tools for implementing anchored popovers, tooltips, and slide-out panels with smooth transitions. It includes a set of accessible form primitives and selection controls to ensure compatibility across different assistive technologies. Its broader capabilities cover the const

The United States Web Design System is a government design system and accessible UI framework. It provides a collection of standardized CSS and JavaScript components, along with a CSS component library, specifically designed for building consistent federal government websites. The system allows for custom CSS theme development through the use of design tokens for colors, spacing, and typography. Users can customize visual themes and compile custom styles to maintain a unified brand identity across multiple web properties. The framework covers responsive interface design and web accessibility

Templ is a type-safe HTML templating engine and UI framework for Go. It provides a system for building reusable HTML components that compile into Go code for server-side rendering, ensuring type safety and compile-time validation of data and logic. The project features a dedicated language server that provides autocomplete and syntax validation for template files within supported code editors. It employs compile-time code generation to transform a custom template language into Go source code, enabling the creation of modular HTML fragments and logic blocks. The framework includes automated s

Theme-ui is a React theme framework and CSS-in-JS utility used for building themeable user interfaces. It functions as a design system tool that establishes centralized, constraint-based scales for colors, typography, and spacing to ensure visual consistency across applications. The framework distinguishes itself through an array-based responsive shorthand for mobile-first layouts and a dedicated color mode manager that synchronizes with browser preferences and persists user selections. It also features a system for creating named style variants to control component appearance via properties

Bit is a component-based development platform and monorepo orchestrator used to build, manage, and share reusable software components across projects. It functions as a system for modular software architecture, providing a component registry for publishing and distributing independent software modules via remote scopes. The platform distinguishes itself through lane-based versioning, which isolates feature development into parallel tracks for comparison and merging. It utilizes a scope-based namespace registry to organize components into hierarchical groups and employs environment-driven comp

Rebass is a React design system library that provides a collection of theme-driven, responsive UI primitives. It functions as a theme-based layout engine, using a set of stateless components to standardize spacing, typography, and colors across a user interface. The library distinguishes itself by mapping style properties to a central design theme through a styled-system approach. This allows for responsive style mapping where components automatically adapt their appearance based on screen size and provides the ability to swap underlying HTML elements while preserving styling logic to maintai

Fomantic-UI is a component-based CSS library and frontend design system used to build consistent, responsive user interfaces. It functions as a CSS framework and responsive UI toolkit, providing a structured approach to managing typography, color palettes, and spacing. The project enables the development of custom UI components and the implementation of unified design systems across web applications. It provides a variable-driven theme compilation process to customize visual styles and a build-time system to compile selected components into production CSS bundles. The toolkit covers a broad

AngularFire is an integration library that wraps the Firebase JavaScript SDK into Angular services and dependency injection patterns. It provides the mechanisms necessary to connect backend authentication, databases, and storage to an application. The library converts live data feeds into observable sequences to synchronize remote data with the application state in real time. It also includes a mechanism for protecting routes by verifying user identity via authentication tokens and a command-line utility to automate the deployment of application builds to hosting services. Additional capabil

This project is a CSS design system framework and modular library providing a standardized set of UI component stylesheets. It establishes a unified system of visual guidelines to ensure a consistent and professional look and feel across web interfaces. The framework is organized as a collection of standalone stylesheets that can be imported individually to minimize bundle size and eliminate unused styles. It utilizes a design token system based on CSS variables to manage theming and a utility-first class system for layout and spacing. The system employs a block element modifier naming conve

Web Components is a set of specifications for creating reusable custom elements with encapsulated styling and logic for the web. It provides a standard for defining new HTML tags that function as independent components across different browser engines. The system is built on three primary pillars: the Custom Elements standard for defining new tags, the Shadow DOM implementation for isolating internal document structures and styles, and the HTML Templates specification for defining reusable fragments of markup that remain inert until instantiated. These capabilities enable modular web design