Blazor Overview: Mastering Web Development with C# and .NET

Blazor Overview: Web Development with .NET

Understanding Blazor in .NET: An In-Depth Overview

Blazor stands out as a groundbreaking framework within the .NET ecosystem, offering a unique approach to web application development. In this comprehensive Blazor overview, we delve into what makes Blazor an innovative choice for developers. Originating from Microsoft’s development labs, Blazor has redefined the landscape of web applications by integrating C# in client-side development. This integration is not just a technical advancement but a strategic expansion of the .NET framework’s capabilities.

Blazor’s journey began in 2018 and has since been evolving, shaping new pathways in web development. Its most notable feature is the ability to run .NET code in web browsers using WebAssembly. This allows for rich, interactive user interfaces and aligns with modern web development trends. As part of this Blazor overview, it’s important to acknowledge how Blazor serves as a bridge, connecting the robustness of .NET with the flexibility of web technologies.

There are two primary models of Blazor: Blazor WebAssembly and Blazor Server. Each serves distinct purposes and caters to different web development needs. Blazor WebAssembly emphasizes client-side processing, enabling dynamic user experiences akin to traditional Single Page Applications (SPAs). Conversely, Blazor Server focuses on server-side processing, ensuring efficient, scalable solutions for complex applications. This Blazor overview aims to highlight how both models offer unique benefits, making Blazor a versatile tool in a developer’s arsenal.

As we delve further into this Blazor overview, we’ll explore its various facets, from setting up the development environment to creating custom components and understanding its advanced features. Blazor is not just another framework; it’s a testament to Microsoft’s commitment to unifying and streamlining web development processes, making it an indispensable tool for developers in the .NET ecosystem.

Blazor WebAssembly vs. Blazor Server

As a part of the ASP.NET Core framework, Blazor provides two hosting models: Blazor WebAssembly and Blazor Server. Understanding the differences between these two is crucial for developers to choose the right approach for their web application.

Blazor WebAssembly Overview

Blazor WebAssembly (often abbreviated as Blazor WASM) is a client-side framework where the application runs directly in the browser using a WebAssembly-based .NET runtime. This model downloads the .NET runtime, application, and its dependencies to the client’s browser. Once downloaded, the application runs entirely on the client-side, interacting with the DOM and other web APIs via WebAssembly.


  • Client-Side Execution: Runs completely in the browser, offering a rich and interactive user experience similar to JavaScript SPAs (Single Page Applications).
  • Offline Capabilities: Can work offline once the application is downloaded.
  • Load Distribution: Offloads work to the client, reducing server load.


  • Initial Load Time: Larger initial download size, leading to slower initial load times.
  • SEO Challenges: As content is rendered client-side, it can pose challenges for search engine optimization.

Blazor Server Overview

In contrast, Blazor Server runs on the server, with the UI updates and event handling being managed over a real-time SignalR connection. In this model, every user interaction is sent to the server, processed, and the required UI updates are sent back to the browser.


  • Reduced Client Requirements: Minimal download size, as the application logic runs on the server.
  • Enhanced Performance on Lightweight Devices: Performs better on devices with limited processing power.
  • SEO Friendly: Easier to manage SEO as the content is pre-rendered on the server.


  • Latency Sensitivity: Depends heavily on network latency, as every user interaction requires server communication.
  • Scalability Considerations: Server resource demands can grow significantly with increased user traffic.

Use-Case Scenarios

  • Blazor WebAssembly is ideal for applications requiring offline support, client-side processing, and where initial load time is not a critical concern.
  • Blazor Server is preferable for applications that need quick initial load times, server-side processing, and where maintaining a persistent connection to the server is viable.

Setting Up the Development Environment

To begin developing Blazor applications, you need to set up a development environment. This process involves installing the necessary tools and software.

Required Tools and Software

  1. .NET Core SDK: Blazor is a part of the ASP.NET Core framework, which requires the .NET Core SDK. The SDK includes everything you need to build and run .NET Core applications.
  2. Visual Studio: Microsoft’s Visual Studio IDE (Integrated Development Environment) is highly recommended for developing Blazor applications. It provides robust project templates, debugging tools, and a powerful editor.
  3. Blazor Templates: For Blazor-specific development, you need to install project templates. These can be easily added to Visual Studio.

Step-by-Step Setup Guide

  1. Download and Install the .NET Core SDK:
    • Visit the .NET Core download page and download the latest version of the .NET Core SDK.
    • Follow the installation instructions for your operating system.
  2. Install Visual Studio:
    • Download Visual Studio from the official website.
    • During installation, select the “ASP.NET and web development” workload, which includes all the necessary components for Blazor development.
  3. Install Blazor Templates:
    • Open a command prompt or terminal.
    • Run the command dotnet new -i Microsoft.AspNetCore.Blazor.Templates to install the Blazor project templates.
  4. Verify Installation:
    • To verify that everything is set up correctly, create a new Blazor project.
    • Open Visual Studio and select “Create a new project.”
    • Choose “Blazor App” from the list of templates.
    • Follow the prompts to create your first Blazor project.

This setup gives you a powerful environment for building Blazor applications. With the .NET Core SDK, Visual Studio, and Blazor templates installed, you’re ready to start your Blazor journey.

Creating Your First Blazor Application

Now that your development environment is ready, let’s dive into creating your first Blazor application. This step-by-step guide will walk you through building a basic Blazor WebAssembly app.

Step 1: Create a New Blazor WebAssembly Project

  1. Open Visual Studio and select “Create a new project.”
  2. Search for “Blazor” and choose the “Blazor WebAssembly App” template. Click “Next.”
  3. Name your project and choose a location for it. Click “Create.”

Step 2: Explore the Project Structure

Once the project is created, you’ll see several files and folders:

  • Program.cs: The entry point for the application.
  • wwwroot: Contains static files like HTML, CSS, and images.
  • Pages: Where your application’s pages are stored.
  • Shared: Contains components used across different pages.
  • App.razor: The root component that sets up routing.

Step 3: Run the Application

  • Click on the “Run” button in Visual Studio to start the application.
  • A browser window will open, displaying your new Blazor app.

Step 4: Modify the Counter Component

Let’s make some changes to the Counter component:

  1. Navigate to the “Pages” folder and open “Counter.razor.”
  2. Find the currentCount variable and the IncrementCount method.
  3. Modify the IncrementCount method to increase currentCount by 2 instead of 1.
  4. Run the application again and click the “Click me” button on the Counter page. You’ll see the count increase by 2 each time.

Code Example:

@page "/counter"


<p>Current count: @currentCount</p>

<button class="btn btn-primary" @onclick="IncrementCount">Click me</button>

@code {
    private int currentCount = 0;

    private void IncrementCount()
        currentCount += 2;

Step 5: Add a New Component

Create a new component to display a message:

  1. In the “Shared” folder, right-click and choose “Add” -> “Razor Component.”
  2. Name it “Greetings.razor.”
  3. Add the following code to the “Greetings.razor” file:
<h3>Hello, welcome to your first Blazor app!</h3>

Step 6: Understanding Data Binding

Modify the “Greetings” component to include data binding:

  1. Add a property in the @code block:
@code {
    public string WelcomeMessage { get; set; } = "Hello, welcome to your first Blazor app!";
  1. Bind this property to the component’s HTML:

Step 7: Run and Test

Run the application again and navigate to the Home page. You will see the “Greetings” component displaying the welcome message.

This simple application demonstrates the basics of Blazor WebAssembly, including project structure, modifying components, and basic data binding. You’ve just taken your first steps into the world of Blazor!

Blazor Components Overview

Blazor applications are built using components. A Blazor component is a self-contained chunk of user interface (UI), such as a page, dialog, or form. Understanding components is key to effective Blazor development.

What are Components in Blazor?

Components in Blazor are .NET classes built with Razor markup. Razor is a syntax for combining HTML markup with C# code. Components in Blazor can be reused throughout the application, making development more efficient and maintainable.

Lifecycle of a Component

Blazor components have a well-defined lifecycle with methods that are executed at specific times during a component’s life:

  1. OnInitAsync/OnInit: Called when the component is initialized.
  2. OnParametersSetAsync/OnParametersSet: Invoked when component parameters are set or changed.
  3. OnAfterRenderAsync/OnAfterRender: Executed after the component has rendered.

Creating Custom Components with Examples

Let’s create a simple custom component that displays a user’s profile information.

  1. Create a New Component:
    • In the “Shared” folder, add a new Razor Component named “UserProfile.razor”.
  2. Add HTML and C# Code:
    • Use the Razor syntax to define the UI and logic.
    • Example code for “UserProfile.razor”. This code creates a component that takes Name and Age as parameters and displays them.
<div class="user-profile">
    <h3>User Profile</h3>
    <p>Name: @Name</p>
    <p>Age: @Age</p>

@code {
    public string Name { get; set; }

    public int Age { get; set; }
  1. Use the Component in a Page:
    • In the “Index.razor” page, use the component:
<UserProfile Name="John Doe" Age="30" />

This renders the UserProfile component with the provided parameters.

Components can also include more complex logic, event handling, and data binding. They are the building blocks of Blazor applications, allowing for modular, testable, and maintainable code.

Data Binding and Event Handling in Blazor

Data binding and event handling are crucial in Blazor for creating interactive and responsive web applications. Blazor provides a simple and consistent way to bind data and handle events.

Data Binding in Blazor

Data binding in Blazor links properties of Blazor components (like input fields, labels, etc.) to C# properties or expressions. It’s a way to synchronize the data between the UI and the application’s state.

Types of Data Binding:

  1. One-Way Binding: Data flows in one direction, typically from a C# property to an HTML element. For example, displaying a property value in a <p> tag.
  2. Two-Way Binding: Data flows in both directions, useful for forms where the input field changes the state, and the state changes the input field.

Example of Data Binding:

<input @bind="name" />
<p>Hello, @name!</p>

@code {
    private string name = "John Doe";

In this example, the text input is bound to the name variable. Changing the input field will update the name, and the <p> tag displays the current value of name.

Event Handling in Blazor

Event handling in Blazor is about responding to user actions like clicks, input changes, form submissions, etc. Blazor allows C# methods to be called in response to these events.

Example of Event Handling:

<button @onclick="ShowMessage">Click Me</button>
@if (isMessageVisible)
    <p>Welcome to Blazor!</p>

@code {
    private bool isMessageVisible = false;

    private void ShowMessage()
        isMessageVisible = true;

Here, clicking the button triggers the ShowMessage method, which changes isMessageVisible to true, displaying the message.

Combining Data Binding and Event Handling

Data binding and event handling often work together. For instance, a form submission can trigger a method that processes the bound data.

Data binding and event handling make it easier to create interactive web UIs with minimal boilerplate code. They are fundamental concepts in Blazor that leverage C#’s power on the web.

Advanced Topics Overview: Dependency Injection and Routing in Blazor

Blazor, being a modern web framework, offers advanced features like Dependency Injection (DI) and Routing, which are essential for developing scalable and maintainable web applications.

Dependency Injection in Blazor

Dependency Injection is a design pattern that Blazor uses to provide components with the services they require. It decouples the creation of a service from its consumption, making components more modular and testable.

  1. Define a Service:
    • Create a service class that provides specific functionality. For example, a WeatherService that fetches weather data.

Implementing Dependency Injection:

  1. Define a Service:
    • Create a service class that provides specific functionality. For example, a WeatherService that fetches weather data.
public class WeatherService
    public Task<string> GetWeatherAsync() => Task.FromResult("Sunny");
  1. Register the Service:
    • In Startup.cs, register the service with the DI container.
  1. Inject the Service in a Component:
    • Use the @inject directive to inject the service into a Blazor component.
@inject WeatherService WeatherService


@code {
    private string weatherForecast;

    protected override async Task OnInitializedAsync()
        weatherForecast = await WeatherService.GetWeatherAsync();

Routing in Blazor

Routing in Blazor allows navigation between different components in the application, similar to navigating between pages in a traditional web application.

Implementing Routing:

  1. Define Routes:
    • In a Blazor component, use the @page directive to specify the route.
@page "/weather"

<h3>Weather Forecast</h3>
  1. Navigate Between Routes:
    • Use NavLink components in the NavMenu.razor for navigation.
    • Set the href attribute to the route defined with the @page directive.
<NavLink href="/weather">
  1. Route Parameters:
    • Routes can also have parameters, allowing dynamic content.
@page "/weather/{Day}"

<h3>Weather Forecast for @Day</h3>

Dependency Injection and Routing are powerful features that enhance the flexibility and maintainability of Blazor applications. They enable the creation of complex, yet organized, web applications.

Conclusion and Future of Blazor

As we wrap up this comprehensive guide on Blazor, it’s evident that Blazor stands as a powerful framework for building interactive web applications using C#. Its integration into the .NET ecosystem offers a seamless development experience for .NET developers, bridging the gap between server-side and client-side development.

Summarizing Key Points

  • Blazor WebAssembly and Blazor Server: We’ve explored the two distinct models of Blazor, each catering to different requirements and scenarios.
  • Ease of Setup: Setting up the development environment for Blazor is straightforward, fostering a smooth entry for developers into the world of Blazor.
  • Component-Based Architecture: The use of components in Blazor promotes reusable, modular, and testable code.
  • Data Binding and Event Handling: These features empower developers to build dynamic user interfaces with ease.
  • Advanced Features: Dependency Injection and Routing enhance the capability to develop scalable and maintainable web applications.

Future of Blazor

The future of Blazor looks promising. With ongoing support and updates from Microsoft, Blazor is continuously evolving. Features like WebAssembly debugging and improved performance are on the horizon. The integration of Blazor with MAUI (Multi-platform App UI) is also an exciting development, indicating a move towards more versatile, cross-platform applications.

Blazor is not just a framework but a paradigm shift in web development for .NET developers. It simplifies the transition from server-side to client-side development, making it an attractive option for many. As web technologies continue to evolve, Blazor is poised to become a key player in the .NET ecosystem, offering a unified approach to building web applications.

In conclusion, Blazor offers a unique blend of productivity, performance, and versatility. Whether you are a seasoned .NET developer or new to web development, Blazor presents an opportunity to build modern web applications with a familiar and powerful language – C#.

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