HeroUI (formerly NextUI)

HeroUI is an open-source React component library designed for building beautiful, accessible user interfaces. It is built on top of Tailwind CSS v4 and React Aria Components, ensuring high-quality animations, polished details, and built-in accessibility (focus management, keyboard navigation, and screen reader support) out of the box.

Key Features

• Accessibility: Built with React Aria Components to meet WCAG standards.
• Customizability: Every component is composed of customizable slots. You can use Tailwind utility classes, CSS variables, or BEM modifiers to style components.
• Developer Experience: Fully typed API with excellent IDE support and autocomplete.
• Performance: Supports Tree Shaking to ensure only the components you use are included in your bundle.
• Modern Stack: Built for React 19 and Tailwind CSS v4, and optimized for AI-assisted development.

HeroUI is a modern React UI component library designed for React 19 and Next.js App Router. It combines accessibility, styling flexibility, and AI-ready tooling.

Core Architecture

• Accessibility-first: Built on React Aria primitives, ensuring robust screen reader support, keyboard navigation, and ARIA compliance out of the box.
• Tailwind CSS v4 Native: Uses CSS-based theming with @theme and design tokens, avoiding the runtime overhead associated with CSS-in-JS.
• Compound Component API: Employs a composable pattern (e.g., Card.Header, Card.Content, Card.Footer) to provide full control over markup and layout.
• Server Component Friendly: Designed with React Server Components (RSC) in mind, featuring minimal and clearly documented client boundaries.

AI Tooling Support

HeroUI provides specialized resources to help AI coding assistants work with its APIs accurately:

• MCP server
• llms.txt
• Agent skills

When to use HeroUI

Ideal for new projects using Next.js, React 19, and Tailwind CSS v4 that require a modern, accessible component library with first-class AI tooling support.

HeroUI is a React UI library designed for enterprise-grade applications, focusing on accessibility, performance, and AI-native developer workflows. It combines the accessibility primitives of React Aria, the styling power of Tailwind CSS v4, and a Compound Component API to provide structural control without prop explosion.

Key Pillars:

• Accessibility: Built on Adobe's React Aria, providing industry-leading WCAG compliance, keyboard navigation, screen reader support, and internationalization.
• Styling: Native support for Tailwind CSS v4 with zero runtime CSS overhead and design tokens defined via standard CSS @theme directives.
• API Pattern: Uses a Compound Component pattern (e.g., Card.Header, Modal.Body) for high structural flexibility and fine-grained styling.
• AI-Native: Provides specialized tools like MCP servers, llms.txt, and Agent Skills to ensure AI coding assistants generate accurate, up-to-date code.

HeroUI and MUI represent different philosophies in component library design.

HeroUI is built for flexibility and modern performance:

• Styling: Uses Tailwind CSS v4 (static CSS), which avoids the runtime overhead of CSS-in-JS.
• Accessibility: Built on React Aria, providing industry-leading accessibility coverage.
• Design: Neutral by default, making it easy to customize via CSS custom properties (design tokens) to match any brand.
• Architecture: Uses a compound component pattern for structural flexibility.
• Best for: New projects using Tailwind CSS, teams prioritizing accessibility, and developers using AI coding tools.

MUI is built around a specific design system:

• Styling: Uses Emotion by default (runtime CSS-in-JS), with Pigment CSS as an experimental option.
• Accessibility: Uses a custom implementation.
• Design: Strictly follows Google's Material Design guidelines. Theming away from Material Design requires significant effort.
• Best for: Projects requiring strict Material Design compliance or specific enterprise features like MUI X (Data Grid, Charts).

HeroUI Native uses a CSS-first approach for styling and theming, which provides several advantages for developers:

• Upgrade-safe customization: You customize the UI by overriding tokens and writing CSS rather than forking component internals, ensuring library updates remain compatible.
• Systemic propagation: Changing a single token (like an accent color or base radius) automatically updates all derived states and sizes across the system.
• Performance-oriented theming: Themes are managed in CSS via Uniwind. Switching themes does not require a React context update to cascade through the component tree.
• Portable themes: A complete visual identity is encapsulated in a stylesheet, making it a shippable, versionable, and installable artifact.
• Consistent vocabulary: The styling system uses the same semantic roles, foreground pairing, and compound component concepts used in the web version of HeroUI.
• AI-friendly: Because design tokens are CSS variables and component styles are CSS classes, the system is easily interpretable by AI assistants via MCP servers or llms.txt endpoints.

HeroUI and Mantine represent two different philosophies for React component libraries:

• HeroUI v3: A focused set of high-quality components built on React Aria for enterprise-grade accessibility. It uses Tailwind CSS v4 for styling and follows a compound component API pattern. It is highly optimized for AI developer tooling (MCP, llms.txt, agent skills).
• Mantine v8: A broad, 'batteries-included' toolkit with over 120 components and 70+ hooks. It uses CSS Modules/PostCSS for styling and provides a large built-in hooks library and form handling (@mantine/form).

Key Decision Factors:

• Styling: Choose HeroUI if you use Tailwind CSS; choose Mantine if you prefer CSS Modules.
• Accessibility: Choose HeroUI for strict WCAG compliance (government, healthcare, finance) due to its React Aria foundation.
• Scope: Choose Mantine for a massive, all-in-one ecosystem; choose HeroUI for a focused, high-depth component set that integrates with best-in-class specialized libraries.