For some time now, within the .NET world there has been growing buzz about Blazor — a technology that lets you build interactive web applications in C# instead of JavaScript. For many C# developers this sounds like a dream come true, because it means building front-end code without needing a separate technology stack. In this article we’ll look at what Blazor is, what its main advantages are, and how it works in practice. At the end you’ll find a short summary and pointers to further learning resources about Blazor.
What is Blazor?
Blazor is an open-source web framework from Microsoft that enables building interactive web applications using the C# language instead of JavaScript. Simply put, Blazor allows you to run real .NET code directly in the user’s browser using WebAssembly. Developers can write a single application in C# which runs both on the server and in the client (browser). Crucially, the user interface is built using UI components (so-called Razor Components) — this component-based approach is similar to modern front-end frameworks like Angular or React, but using Razor syntax and C# instead of JavaScript.
In practice, building UI in Blazor means mixing HTML markup with C# code in the same component file. You can handle events (e.g. button clicks) with C# methods, and bind data displayed on the page directly to fields/variables in your code. Below is a simple example of a Blazor component (a counter) illustrating this concept:
@page "/counter"
<h3>Counter</h3>
<p>Value: @count</p>
<button @onclick="Increment">Add</button>
@code
{
private int count = 0;
private void Increment()
{
count++;
}
}As you can see, the component contains HTML markup (<h3>, <p>, <button>) and C# snippets prefixed with @. The expression @count renders the current value of the count variable in the UI, and the attribute @onclick="Increment" binds the button click event to the Increment C# method. Thus the entire interaction logic runs in C# — we don’t need a single line of JavaScript for the counter to work.
Advantages of Blazor
Blazor is gaining popularity for several important reasons. Below are its major advantages:
• One language across the whole application: Both front-end and back-end can be written in C#, simplifying work for .NET teams and making code maintenance easier. You no longer need to juggle multiple languages — eliminating the context switch between C# and JavaScript.
• No need for JavaScript (in many cases): Interactive UI logic can be written in C#, so in many scenarios you can avoid writing JavaScript on the client side. For C# developers, this means faster learning of front-end development and reuse of existing .NET skills.
• Component model and intuitive syntax: Blazor uses a component-based architecture and Razor syntax, which simplifies UI development. You build small, independent UI components you can reuse across the application. The structure and concepts are close enough to modern frameworks (e.g. Angular) that those with front-end experience can adapt easily.
• Performance and responsiveness: Blazor apps can perform very well — the framework is designed so the UI reacts quickly and smoothly to user actions. With proper app design, performance can rival native JavaScript apps, while leveraging the advantages of the .NET ecosystem (strong typing, rich standard library, developer tooling).
Of course, Blazor isn’t a “silver bullet” and has certain limitations. But benefits such as using C# on the front-end, component architecture, and technological consistency across the app make many teams see Blazor as a potential game changer in the .NET ecosystem.
Hosting Models of Blazor
Blazor offers two main models for running applications: Blazor Server and Blazor WebAssembly (client). Each approach differs in how code is executed, and each has strengths and trade-offs. Below we briefly explain both models.
Blazor Server: In this model, the Blazor application runs on the server (inside an ASP.NET Core app), and the client browser acts as a “terminal” displaying UI. When the app loads, the browser fetches just the needed code to establish a connection. Then all user interactions (clicks, input, etc.) are sent from the browser to the server via SignalR (WebSockets). The server executes logic and sends back UI updates for the browser to apply. Blazor Server’s key advantages: initial payload is minimal, responsive even on weak devices, and server-side code stays secure. Downsides: every action must round-trip, requiring a stable connection; scalability is a challenge when many users connect.
Blazor WebAssembly: Here the application runs entirely in the client browser using WebAssembly. On load, the browser downloads the .NET runtime, assemblies, and app code. Once loaded, UI rendering and event handling happen in the browser locally, without needing constant server communication. The server only acts to serve data (APIs, files). Advantages: offline capability, local UI responsiveness, reduced server resource load. Limitations: larger startup download, exposing client code, browser sandbox constraints, dependency on modern browsers.
A note: from .NET 8 onward there's a hybrid model sometimes called Blazor United / Blazor Web App, which brings together Server and WebAssembly approaches — e.g. server-render part of the app for faster first load, then switch to WebAssembly. This flexibility is a significant improvement over earlier restrictions.
Summary
Blazor is undeniably one of the more transformative innovations in the .NET ecosystem in recent years. It bridges front-end and back-end, allowing .NET developers to build advanced, responsive web apps using already known C#. For those new to web development, Blazor can be a great starting point — it removes much of the complexity of JavaScript by converging on a single language and platform.
As a relatively young framework, Blazor is still maturing — the volume of materials and community support is smaller than for veterans like Angular or React. But the community is growing fast, and each .NET version brings enhancements. If you're curious about building web apps without diving deep into JavaScript, Blazor is definitely worth a try. Many companies already use it in production — maybe now is your turn to try your first Blazor app and see what it can do.
Blazor School
By the way, if you’d like to learn Blazor more thoroughly, consider joining my online training Blazor-School (more info at: blazor-school.com). In this course we go step by step through building modern Blazor apps — from basic concepts to advanced techniques. It's a solid way to master Blazor practically and become a Full-Stack .NET developer without needing to learn JavaScript.
