Today we are thrilled to publish the first Release Candidate of the Fluent UI Blazor library v5! This major release marks a significant evolution for the library, bringing a new foundation built on top of the latest Fluent UI Web Components, powerful new components, a game-changing Default Values system, and first-class Localization support. 

Let me walk you through what?s new and why we think v5 is the best     version of Fluent UI Blazor library yet.

We Are .NET

Microsoft Fluent UI Blazor library v5 RC1 is now available, built on Fluent UI Web Components v3 — the same components powering Microsoft 365, Teams, and Windows 11. Key changes include a new area-based FluentLayout component for full-page layouts, a Default Values system for setting global component parameter defaults in Program.cs, and built-in localization support via IFluentLocalizer. The migration from v4 requires some code changes due to attribute name alignment with Fluent UI React, but documentation and an MCP server are provided to assist. Bundle size is reduced by dropping the legacy FAST dependency, and WCAG 2.1 AA accessibility compliance is included out of the box.

What's new for the Microsoft Fluent UI Blazor library 5.0 RC1

A New Foundation: Fluent UI Web Components 3