Fluent UI Web: A Comprehensive Overview of React Components v9, React v8, and Web Components

Fluent UI Web is a robust collection of utilities, React components, and Web Components designed to empower developers to build polished, accessible, and scalable web applications. The Fluent UI ecosystem today is organized around three interrelated projects that cover different use cases and migration paths. This post dives into what each project brings to the table, how they relate to one another, and why teams might choose one path over another as they adopt Fluent UI in their apps.

Introduction to Fluent UI Web centers on a simple truth: Fluent UI is not a single library, but a family of packages that enables progressive adoption. The v9 release for Fluent UI React Components marks a major milestone, paving the way for a more forward-looking, future-proof approach. At the same time, Fluent UI retains mature, battle-tested options in its v8 React components and a Web Components implementation for those who prefer browser-native components without a React dependency. Below is a guided tour of the three distinct projects and how teams can navigate them to achieve a smooth, well-supported migration.

Three Projects at a Glance

• React Components (v9)

• Overview: This is the newest, forward-looking iteration of Fluent UI React components. v9 is designed to be the modern, future-proof core of Fluent UI on the React platform, bringing streamlined APIs, improved performance, and a focus on accessibility and consistency across experiences.

• Read Me: The primary documentation and setup guidance live in the React components package readme, which provides quick-starts, patterns, and component-level examples.

• Changelog: Ongoing changes and improvements are tracked in the CHANGELOG for the React components package, helping teams understand what’s new, what’s fixed, and what may require adaptation in their apps.

• Repository: The React components live in a dedicated package path within the Fluent UI repository, with its own governance, issues, and contribution guidelines.

• Quick Start: A developer-friendly Quick Start guide is available to help teams bootstrap Fluent UI React Components in their applications and begin building immediately.

• Documentation: Comprehensive docs cover usage, components, patterns, and best practices for building contemporary Fluent UI experiences.

• NPM Package: The package name is @fluentui/react-components, and it ships the latest v9 components with a focus on consistency and future readiness.

• Version, Issues: The v9 line receives ongoing maintenance, new features, and fixes. Public issue trackers host discussions about bugs, enhancements, and migration questions.

• Practical takeaway: For teams starting anew or migrating a modern React codebase, v9 offers the cleanest API surface and the newest design-system capabilities.

• React (v8)

• Overview: Fluent UI React v8 represents a mature and widely used generation of the Fluent UI React ecosystem. It remains a stable, feature-rich option for teams with established codebases that depend on its patterns and components.

• Used By: This version is strongly associated with Microsoft 365 apps and related experiences that rely on stable, battle-tested components.

• Read Me, Changelog, Repo: The v8 components maintainers provide documentation, changelog entries, and structural guidance in their respective package scope.

• Quick Start, Docs, NPM, Version, Issues: For ongoing projects that are already aligned with v8, continued support and migration planning are essential as teams evaluate moving toward v9.

• Practical takeaway: If your project is already deeply integrated with v8, migration planning should be considered in stages to minimize risk while gaining access to newer capabilities.

• Web Components

• Overview: Fluent UI Web Components deliver a Web Component implementation of Fluent UI. This project targets environments where a framework-agnostic approach is preferred or where a lighter dependency footprint is desirable.

• Read Me, Changelog, Repo: The Web Components package has its own documentation and release history, guiding developers through the specifics of using Fluent UI in a non-React context.

• Quick Start, Docs, NPM, Version, Issues: Web Components provide a path to use Fluent UI without React, with patch-level updates and community-driven improvements.

• Practical takeaway: Choose Web Components if you’re looking for framework independence or want to embed Fluent UI experiences into a broader mix of technologies.

Migration and Interoperability: A Pragmatic Path to Fluent UI

One of the strengths of Fluent UI Web today is the ability to combine components across generations. You can leverage Fluent UI React v9 components alongside v8 components or even with v0 components, enabling a gradual migration rather than an immediate rewrite. This interoperability is intentional, designed to help teams transition at their own pace while maintaining a consistent design language and user experience.

Key points about migration:

• You can adopt v9 components in new sections of an app and progressively replace older v8 components as you consolidate patterns and ensure compatibility.
• The migration overview provides structured guidance on mapping v8 to v9 component equivalents, easing the transition for large codebases.
• Gradual migration reduces risk, allows UX and accessibility improvements to ship incrementally, and minimizes the blast radius of refactors.

FluentUI Insights: A Glimpse into Design Decisions

Fluent UI Insights is a series that sheds light on the design decisions behind Fluent UI’s approach to the design system. The show aims to explain how choices in positioning, styling, Griffel (the CSS-in-JS engine), theming, and accessibility shape the final product. The insights are presented as a sequence of episodes, each focusing on a core topic and offering practical explanations that help teams reason about components, tokens, and patterns.

• EP01: Positioning

• A visual overview of how Fluent UI handles layout, alignment, and responsive behavior across components.

• Visual resources: Watch EP01: Positioning

• EP02: Styling

• An exploration of the styling system that powers Fluent UI components, including how styles are authored, composed, and optimized for performance.

• Visual resources: Watch EP02: Styling

• EP03: Griffel

• A deep dive into Griffel, Fluent UI’s foundational styling engine, and how it enables fast, deterministic CSS generation.

• Visual resources: Watch EP03: Griffel

• EP04: Foundational APIs

• A look at the core APIs that developers interact with, including slots, JSX patterns, and fundamental hooks and utilities.

• Visual resources: Watch EP04: Foundational APIs

• EP05: Theming

• An exploration of theming in Fluent UI, including how tokens, palettes, and semantic colors drive consistent experiences.

• Visual resources: Watch EP05: Theming

• EP06: Accessible by Default

• A discussion on accessibility considerations baked into Fluent UI components, ensuring that default behaviors promote inclusivity.

• Visual resources: Watch EP06: Accessible by default

Licenses and Open Source Ethos: How Fluent UI Is Shared with the Community

All files in the Fluent UI React GitHub repository are released under the MIT license. This permissive license is chosen to encourage broad use and contribution while maintaining a clear license framework for developers and organizations. The license page at the root of the repository provides the exact terms and conditions.

Additionally, the use of fonts and icons in Fluent UI is governed by the assets license agreement. If you plan to work with the typography and iconography assets in Fluent UI, be aware of the licensing terms that apply to those assets. The assets license agreement helps ensure that these visual resources are used in ways that respect the original design intentions and legal permissions.

Changelog and Looking Ahead: How Changes Are Communicated

Each Fluent UI package maintains its own changelog, detailing additions, fixes, and changes. This per-package changelog system makes it easier for teams to understand the specific impact of an update on the components they rely on. When planning migrations or upgrades, developers can review the relevant changelog sections to identify breaking changes, deprecations, or new capabilities and plan accordingly.

Where to Look Next:

• For Fluent UI React (v9) components, consult the CHANGELOG.md inside the React components package.
• For Fluent UI React (v8) components, consult the CHANGELOG.md inside the React package.
• For Web Components, consult the CHANGELOG.md inside the Web Components package.

Looking for Office UI Fabric React? A Transition to Fluent UI

If you’re familiar with Office UI Fabric React, you’ll notice an evolution that converges around Fluent UI. The Office UI Fabric React project has progressed into the Fluent UI umbrella, and the repository that previously hosted office-ui-fabric-react is now consolidated under Fluent UI. The new naming and package structure reflect the new design language and open-source strategy. In practical terms, your Fabric code can be migrated to Fluent UI packages such as @fluentui/react for React-based experiences, with a migration guide helping you map old components to their Fluent UI v9 counterparts.

Looking for Fluent UI React Northstar? A Tale of Evolution and Supersession

Fluent UI React Northstar has been superseded by Fluent UI React Components v9 and reached End Of Life in July 2025. For teams seeking the Northstar experience, the recommended path is to adopt Fluent UI React Components v9 or its related Web Components where appropriate. Details about Northstar’s source and README remain accessible for historical context, but ongoing development and support are aligned with the v9 ecosystem.

Code of Conduct and Community Etiquette

This project has adopted the Microsoft Open Source Code of Conduct. The code of conduct outlines expectations for respectful collaboration, reporting of concerns, and the manner in which issues, pull requests, and discussions should be conducted. For more information, consult the Code of Conduct FAQ or contact [email protected] with any questions or comments.

Putting It All Together: Why Fluent UI Web Matters for Modern Web Apps

• Consistency Across Platforms: Fluent UI is designed to deliver a consistent look, feel, and interaction model across React components, Web Components, and the broader web ecosystem. This consistency reduces the cognitive load for users and simplifies maintenance for developers.
• Migration-Friendly Architecture: By supporting both v9 React components and older v8/v0 elements, Fluent UI makes it practical to modernize incrementally. Teams can reap the benefits of the latest design system while keeping critical parts of their apps stable.
• Accessibility-First by Default: The Fluent UI design principles emphasize accessible-by-default patterns, ensuring that components are usable by a broad audience and compliant with common accessibility standards.
• Open Source Collaboration: The MIT license and transparent changelogs invite community involvement. Contributions, bug reports, and feature requests help Fluent UI evolve in alignment with real-world use cases.

A final note on how to approach Fluent UI Web in your organization

• Start with a quick audit of your current UI components. Identify areas where v9’s modern patterns would yield immediate benefits, such as improved accessibility tokens, better theming, or streamlined performance.
• Map v8 components to their v9 equivalents to outline a staged migration plan. Focus first on areas of your app that are due for a refresh or where performance and accessibility gains would have outsized impact.
• Consider Web Components for part of your stack if you’re integrating Fluent UI into a framework-agnostic environment or need to embed UI elements in non-React contexts.
• Leverage Fluent UI Insights episodes as a learning resource for design-system decisions. The series helps translate design decisions into practical component usage.

Images and Visual References from the Input

The following visuals accompany the narrative, illustrating status, contributions, top language, and the Fluent UI Insights episodes:

• Build status, contributor metrics, top language, and Twitter follow badges at the top of this post.
• Fluent UI Insights EP01–EP06 GIF previews:
• EP01: Positioning
  • Watch EP01: Positioning
• EP02: Styling
  • Watch EP02: Styling
• EP03: Griffel
  • Watch EP03: Griffel
• EP04: Foundational APIs
  • Watch EP04: Foundational APIs
• EP05: Theming
  • Watch EP05: Theming
• EP06: Accessible by Default
  • Watch EP06: Accessible by default

Conclusion: Embracing Fluent UI Web for a Seamless Development Experience

Fluent UI Web represents a thoughtful, flexible approach to building modern web interfaces. Whether you’re starting fresh with Fluent UI React Components v9, maintaining a mature v8 codebase, or exploring a framework-agnostic Web Components path, Fluent UI provides the tools, patterns, and governance to help teams deliver polished, accessible, and cohesive experiences. The design system’s ongoing evolution—guided by migration-friendly strategies, insightful design discussions, and an open-source ethos—ensures Fluent UI remains relevant as the web ecosystem grows and the needs of users expand.

If you’re planning a UI refresh, consider how the three projects fit your roadmap:

• Use React Components (v9) for new functionality and forward-looking experiences with modern APIs.
• Retain and maintain v8 components where stability and existing integrations are paramount.
• Introduce Web Components where framework independence or cross-framework embedding is advantageous.

By embracing the best of each path and leaning on the migration guidance, teams can deliver consistent, accessible, and delightful user interfaces without compromising velocity. Fluent UI Web is not just a set of widgets—it’s a strategic framework for evolving modern web applications in a thoughtful and collaborative way.