Q&A

Mastering Blazor Authentication and Authorization

• By David Ramel
• 04/01/2025

Blazor continues to make waves in the .NET ecosystem by offering a powerful and flexible UI framework that allows developers to build rich, interactive web applications using C# instead of JavaScript. As it matures, more developers are exploring how Blazor fits into their cross-platform strategies -- especially with the advent of Blazor Hybrid via .NET MAUI, which allows the same Blazor components to run across browser, desktop, and mobile environments.

One area that's critical in any production application is user identity. Whether building a line-of-business web portal or a cross-platform app, developers need to handle authentication (who a user is) and authorization (what a user can do). In Blazor, these security concerns can vary depending on the hosting model -- whether it's server-side, WebAssembly, or part of a .NET MAUI Hybrid app. Understanding how to implement these patterns securely and efficiently is key to delivering polished, user-friendly applications.

At the upcoming Visual Studio Live! @Microsoft HQ developer conference, longtime Microsoft technology expert Rockford Lhotka will demystify this essential topic in his session, "Blazor Authentication and Authorization." He'll walk attendees through the ins and outs of authentication across Blazor Server, WebAssembly, and .NET MAUI Hybrid apps, and show how to use identity and claims to customize application behavior through fine-grained authorization.

We caught up with Lhotka, VP of Strategy at Xebia and a veteran observer of multiple UI technology shifts in the .NET world, to learn more about what makes Blazor stand out -- and what developers can expect to take away from his upcoming session.

VisualStudioMagazine: What inspired you to present a seminar on this topic?
Lhotka: I have used every UI framework in the Microsoft space since Visual Basic in 1991. Each framework has built on the lessons learned from its predecessors, and Blazor is the best UI framework so far. It builds on the ubiquitous HTML/CSS world, combining that with data and event binding that is more powerful than XAML, and UI composability that is beyond anything in the past.

I'm very excited about the potential Blazor offers to developers from web, desktop, and mobile backgrounds, and want to share that enthusiasm with others.

What are the key advantages of using Blazor over traditional JavaScript-based web frameworks?
Many of today's web UI frameworks are very powerful and productive -- if you know HTML, CSS, JavaScript, TypeScript, and the numerous tools and other elements of the UI framework's ecosystem. If you are a .NET developer, becoming proficient in any of those frameworks can be a very steep learning curve.

Blazor offers an alternative, where you can build the same rich browser-based user experiences by using the tools, platform, and language that you already know and understand. You need to know or learn HTML and CSS, but all your .NET and C# knowledge and experience directly applies to Blazor.

This means that you can continue to leverage your existing IDE, tools, libraries, and language to build compelling user experiences without having to go through the learning curve of an entirely different set of technologies.

How can developers integrate existing JavaScript libraries into Blazor applications effectively?
In most cases a Blazor developer can build fantastic user experiences directly in Blazor with C#, HTML, and CSS. There are times however, where the rich array of preexisting JavaScript libraries can be extremely useful as well.

Fortunately, Blazor provides a great way to interoperate between Blazor and JavaScript. Your Blazor code can invoke JavaScript functions and libraries, and those libraries can call back into your C# code.

This allows you to tap into things like Firebase for authentication, or JavaScript libraries that provide dynamic charting or other UI behaviors that may fit great into your app and meet your business requirements.

How does Blazor compare to other UI frameworks when modernizing legacy applications like WPF and Windows Forms?
In my mind, the first question you need to answer when modernizing Windows Forms or WPF apps is whether you need to be cross-platform. If your users will be forever happy running your apps only on Windows, then you need to seriously consider just upgrading your existing apps to modern .NET to get away from .NET Framework.

Most users do want cross-platform, and don't want to be limited to only Windows when using modern apps. This is where Blazor really shines, because you can leverage your knowledge of Visual Studio, C#, .NET, and the .NET ecosystem to build a modernized version of your legacy app that runs in any modern browser.

Yes, you'll need to learn the Blazor UI framework along with some HTML and CSS. This is no different than moving to any new UI framework throughout the history of the Microsoft technology stack. At the same time, you avoid spending untold hours learning entirely new languages, dev tools, and ecosystems.

WPF built on lessons learned from the Windows Forms UI framework to create something more productive and powerful. Blazor does the same thing with WPF, taking the lessons learned from XAML and combining them with the ubiquitous HTML/CSS languages used in nearly all modern user experiences. Blazor also takes visual composition to the next level, enabling reuse of "user controls" and similar concepts in ways that weren't possible in Windows Forms or WPF.

Thanks to the MAUI hybrid technology, you can even use Blazor to build native Windows (and iOS, Android, and Mac) apps that have full access to the underlying operating system, just like you can with Windows Forms and WPF.

What resources would you recommend for attendees to get up to speed on Blazor and prepare for your seminar?
My seminar assumes no knowledge of Blazor, but it is in your best interest to have familiarity with .NET, C#, and Visual Studio (or VS Code). It is also helpful if you have some basic knowledge of HTML and at least some exposure to CSS.

Fortunately, one of the primary advantages of using HTML and CSS is that the internet is overflowing with examples and tutorials that provide basic understanding of these languages. Sharing that sort of knowledge is a core aspect of web development, so people have been sharing this information for decades.

Note: Those wishing to attend the session can save money by registering early, according to the event's pricing page. "Save $200 when you register by the Early Bird savings deadline of April 11," said the organizer of the event, which is presented by the parent company of Visual Studio Magazine.