What Is Blazor and How to Build Your First Web App Using C# Instead of JavaScript?

Introduction

In modern web development, JavaScript has been the dominant language for building interactive web applications. However, many developers who are comfortable with C# often wonder if they can build web apps without relying heavily on JavaScript.

This is where Blazor comes into the picture.

Blazor is a powerful web framework from Microsoft that allows you to build interactive web applications using C# instead of JavaScript. It is part of the .NET ecosystem and is gaining popularity among developers who want to use a single language across both frontend and backend.

In this article, we will understand what Blazor is, how it works, its different types, and step-by-step how to build your first Blazor web application using C# in a simple and practical way.

What Is Blazor?

Blazor is a modern web framework that allows developers to create web applications using C# and .NET instead of JavaScript.

In simple words, Blazor lets you write frontend code (UI logic) in C#, which normally requires JavaScript.

It uses technologies like WebAssembly and SignalR to run your C# code in the browser or on the server.

Real-life analogy:

Think of Blazor as a bridge that allows C# developers to enter the world of web development without learning JavaScript deeply.

Why Use Blazor for Web Development?

Blazor offers several advantages that make it attractive for developers.

First, you can use C# for both frontend and backend, which reduces the need to switch between multiple languages.

Second, it improves productivity because you can reuse existing .NET libraries and code.

Third, it provides strong typing, which helps catch errors early.

Fourth, it integrates seamlessly with Visual Studio and the .NET ecosystem.

Finally, it simplifies full-stack development for developers who already know C#.

Types of Blazor Applications

Blazor mainly comes in two types:

Blazor Server

In Blazor Server, the application runs on the server, and UI updates are sent to the browser using SignalR.

Key points:

Faster initial load
Requires constant server connection
Good for internal apps

Blazor WebAssembly

In Blazor WebAssembly, the application runs directly in the browser using WebAssembly.

Key points:

Runs completely on client-side
Works offline (with limitations)
No constant server connection required

How Blazor Works Behind the Scenes

Blazor uses a component-based architecture. Each part of the UI is built using reusable components written in C# and Razor syntax.

When a user interacts with the UI:

In Blazor Server → Events are sent to server and UI updates are returned
In Blazor WebAssembly → Everything runs inside the browser

This makes development similar to modern frameworks like React or Angular, but using C#.

Prerequisites to Build Your First Blazor App

Before you start, make sure you have the following installed:

.NET SDK (latest version)
Visual Studio or Visual Studio Code
Basic knowledge of C#

You can check installation using:

dotnet --version

Step-by-Step: Create Your First Blazor Web App

Let’s build a simple Blazor application step by step.

Step 1: Create a New Blazor Project

Open terminal or command prompt and run:

dotnet new blazor -n MyFirstBlazorApp
cd MyFirstBlazorApp

Step 2: Run the Application

dotnet run

Open your browser and navigate to:

https://localhost:5001

You will see your Blazor app running.

Step 3: Understand Project Structure

Important folders:

Pages → Contains UI pages
Shared → Reusable components
wwwroot → Static files (CSS, images)

Example file:

@page "/counter"

<h3>Counter</h3>

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

<button @onclick="IncrementCount">Click me</button>

@code {
    int count = 0;

    void IncrementCount()
    {
        count++;
    }
}

This is a simple interactive component written entirely in C#.

Step 4: Modify the UI

You can edit components to customize your app.

Example:

<h3>Hello Blazor</h3>

<input @bind="name" placeholder="Enter your name" />

<p>Hello, @name!</p>

@code {
    string name;
}

This creates a dynamic UI without JavaScript.

Real-World Example: Simple Form App

Let’s create a basic form.

<h3>User Form</h3>

<input @bind="username" placeholder="Enter username" />
<button @onclick="Submit">Submit</button>

<p>@message</p>

@code {
    string username;
    string message;

    void Submit()
    {
        message = "Welcome " + username;
    }
}

This example shows how easily you can handle user input using C#.

Advantages of Using Blazor

Blazor provides many benefits for modern web development.

You can use a single language (C#) across the entire application.

It reduces dependency on JavaScript frameworks.

It allows code sharing between client and server.

It improves developer productivity and maintainability.

Disadvantages of Blazor

Despite its advantages, Blazor has some limitations.

Initial load time in WebAssembly can be higher.

It is still evolving compared to older JavaScript frameworks.

Some browser features may still require JavaScript interop.

When Should You Use Blazor?

Blazor is a great choice when:

You are a C#/.NET developer
You want to build full-stack applications
You prefer strong typing and structured code
You want to reuse existing .NET logic

Before vs After Scenario

Before Blazor:

You needed JavaScript for frontend and C# for backend.

After Blazor:

You can build both frontend and backend using C#.

This simplifies development and reduces complexity.

Summary

Blazor is a modern and powerful framework that allows you to build web applications using C# instead of JavaScript. It simplifies full-stack development, improves productivity, and enables developers to reuse their existing .NET skills. By understanding its concepts and building simple applications step by step, you can quickly start developing interactive and professional web applications using Blazor.