Blazor for Beginners: What It Is and How It Works

Blazor is a .NET web UI framework that lets you build interactive interfaces using C# and Razor components. A Blazor application is built from reusable components that combine markup with application logic.

🚀 Try Razor event handling in the MAUI Playground

What is a component?

A component is a reusable UI unit. It can contain markup, C# logic, parameters, event handling, and component state.

<h1>Hello, Blazor!</h1>
<button @onclick="Increment">Clicks: @count</button>

@code {
    private int count;

    private void Increment() => count++;
}

The button event changes the component's state. Blazor can then render the updated UI so the displayed count reflects the new value.

Parameters

Components can receive data from their parent components through parameters. This lets the same component be reused with different values instead of duplicating markup.

Server and WebAssembly

Blazor supports different hosting models. Blazor Server processes application logic on the server and maintains an interactive connection with the browser, while Blazor WebAssembly runs .NET code in the browser. Modern Blazor also supports mixed rendering approaches, so the exact hosting model depends on the application architecture and .NET version.

Dependency injection

.NET dependency injection can be used from Blazor components. Services such as application state, HTTP clients, or domain services can be registered with the application's service collection and injected where required.

JavaScript interop

Blazor can call JavaScript when browser functionality is easier to access from JavaScript. This is useful for APIs or libraries that do not have an equivalent .NET abstraction, but interop should be kept at clear boundaries.

Why learn Blazor?

If you already know C# and .NET, Blazor provides a natural way to build interactive web interfaces without making JavaScript your primary application language. It is especially useful when you want to share concepts and services across a broader .NET application.

Common beginner mistakes

• Changing component state without understanding when the component re-renders.
• Putting browser-only JavaScript calls in places where prerendering or server execution can occur.
• Making every piece of UI one huge component instead of separating reusable responsibilities.

Next step

Continue with the Blazor Tutorials pillar for components, parameters, JavaScript interop, SignalR, and hosting models.