What’s New in Blazor: .NET 10 Preview Highlights

1. Smarter Form Validation

Form validation just got a lot stronger. Blazor now supports validating nested object properties and collection items—something that used to require extra manual wiring. To unlock it:

• Register validation via builder.Services.AddValidation() in your Program.cs
• Declare your form model types in plain C# files (not razor pages)
• Annotate the root model with [ValidatableType]

This gives you more predictable, comprehensive validation with minimal setup.Reddit

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2. Passkey Authentication Made Easier

Blazor apps now offer improved out-of-the-box support for passkey authentication. With updated APIs and built-in scaffolding (especially in the Blazor Web App—or "United"—templates), developers can more easily integrate modern, passwordless logins.InfoQ

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3. Build-Time Service Validation for WebAssembly

One notable strengthening: Blazor WebAssembly apps now check that all configured services are valid during build-time, not only at runtime. This means missing or misconfigured dependencies get caught early—preventing runtime errors.Reddit

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4. Sharper Tooling & Naming

Some “under the hood” improvements include:

• Renamed components and improved APIs for greater clarity
• Metrics updated to follow OpenTelemetry naming conventions
• OpenAPI.NET upgraded to a stable version
• Fixes to form-data metadata handling and XML doc merging for OpenAPI generationInfoQ

5. Blazor Web Script Now Smaller and Smarter

.NET 10 continues optimizing asset pipelines. As part of that, blazor.web.js—the core framework script—is now delivered with fingerprinting and precompression like other static assets. That drives down its size dramatically (from ~183 KB to ~43 KB), improving load times and caching effectiveness.Telerik.com

6. Easier UI & Navigation Experience

Several enhancements make interactive apps smoother:

• QuickGrid now supports row-level styling using a RowClass delegate—no more manual CSS hooks.Syncfusion Blazor Demos
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• Using NavigateTo to navigate within the same page no longer scrolls to the top—preserving scroll position for better UX.Telerik.com
• NavLink can now ignore query strings and fragments when using Match="NavLinkMatch.All"—so your active menu doesn't flicker.Telerik.com
• The reconnection UI is now included by default in templates, with new events and states like retrying for handling client–server disconnections more gracefully.Telerik.com

Why These Updates Matter (Even Without Code Examples)

• Better validation means less runtime guessing and fewer bugs during development.
• Stronger authentication options keep your app future-ready and secure with modern standards.
• Build-time checks reduce “it worked on dev but failed in production” surprises.
• Name clarity and tooling improvements lead to more readable and maintainable code.
• Smaller framework scripts keep apps fast and lean.
• UX refinements in navigation and connectivity make apps feel polished, even under poor network conditions.

Final Thoughts

Blazor is swiftly becoming Microsoft’s go-to strategy for .NET web UI—both on the server and in the browser. These enhancements in .NET 10 Preview 7 show a continued commitment to developer productivity and app performance.

If you'd like, I can craft a Markdown version of this article, or help you outline these changes for an internal newsletter or team update—just say the word!