What New Features and Enhancements Does ASP.NET Core 10 Bring to Blazor, APIs, Security, and Developer Performance?

Introduction :

With the arrival of .NET 10, Microsoft continues its mission to make ASP.NET Core faster, more secure, and easier to use for web and cloud apps. This release delivers notable upgrades in Blazor, Minimal APIs, OpenAPI, authentication, and overall framework performance, making it one of the most developer-focused ASP.NET Core updates in recent years.

Let’s break down the most important improvements and what they mean for developers building modern applications today.

Blazor Gets Smarter, Faster & More Capable

Blazor — Microsoft’s C#-based web UI framework — receives some of the largest changes in .NET 10, improving both WebAssembly performance and developer ergonomics.

Performance Improvements

ASP.NET Core 10 introduces:

Preloaded static assets to reduce WebAssembly startup time
Better diagnostics and profiling tools to analyse performance

These upgrades result in smoother user experiences — especially for applications with large UI bundles.

Better Validation & State Handling

Full object-graph validation now allows validating nested and complex models — boosting reliability in form-heavy applications.
Blazor Server gains persistent component state, enabling session restoration after disconnections — extremely useful for enterprise dashboards or long-running forms.

QuickGrid Enhancements for Better UI

The popular Blazor QuickGrid component now supports:

RowClass — letting you apply conditional row styling using C#
Improved navigation prevents accidental page jumps
Cleaner, more maintainable UI logic

Example — conditional styling using RowClass:

<QuickGrid Items="items"
           RowClass="GetRowCssClass">
    <PropertyColumn Property="@(p => p.Name)"
                    Title="Name" />

    <PropertyColumn Property="@(p => p.IsArchived)"
                    Title="Archived" />
</QuickGrid>

@code {
    private string? GetRowCssClass(MyGridItem item)
    {
        return item.IsArchived
            ? "archived-row"
            : null;
    }
}

OpenAPI and Minimal APIs — Better for Modern API-Driven Apps

The API development experience becomes sharper, more standards-driven, and less verbose.

Full OpenAPI 3.1 Support

ASP.NET Core 10 now ships:

Native OpenAPI 3.1 compatibility
YAML output support
Improved XML comment parsing
Better schema generation

This means APIs can now produce more accurate documentation, aligned with current industry specifications.

Minimal APIs Get Built-In Validation

Minimal APIs now support automatic validation using DataAnnotations:

app.MapPost("/person", ([Validate] Person person) =>

Results.Created($"/person/{person.Id}", person));

If validation fails, ASP.NET Core responds with a 400 Bad Request — automatically.

Leaner Code, Less Boilerplate

You can now inject services directly without [FromServices]:

Old way

app.MapGet(
    "/users",
    ([FromServices] IUserService userService) =>
        userService.GetAllUsers()
);

.NET10way

app.MapGet(
    "/users",
    (IUserService userService) =>
        userService.GetAllUsers()
);

This makes Minimal APIs even more attractive for microservices and serverless workloads.

Authentication & Security — Passwordless Future, Better Protection

Security continues to be a major focus for Microsoft.

New Features Include:

Passkey authentication (WebAuthn + FIDO2) for password-free sign-ins
More secure than passwords, resistant to phishing
Built-in identity metrics to track login attempts & failures
APIs return 401 or 403 instead of redirecting to login automatically
Better aligned with REST standards
RedirectHttpResult.IsLocalUrl — protecting apps from open-redirect vulnerabilities

Together, these make authentication simpler, safer, and more monitorable.

Developer Productivity & Performance Enhancements

Even without writing new code, your application becomes faster just by recompiling on .NET 10 — thanks to framework-level optimizations.

Productivity Boosts

The [Route] attribute now has syntax highlighting in Blazor — easier route visualization
Improved diagnostics & optional suppression of noisy exception logs
Full support for Server-Sent Events (SSE) — a lightweight alternative for real-time updates

Local Development Improvements

.localhost is now treated as a secure loopback domain in Kestrel
making local HTTPS development easier and clearer
Kestrel memory optimizations & automatic eviction reduce hosting costs

Conclusion :

ASP.NET Core in .NET 10 is not just a routine update — it is a meaningful upgrade that enhances productivity, speeds up applications, simplifies API development, and brings modern authentication to the mainstream.