What is Blazor?

Blazor is a Microsoft framework that lets you build interactive web pages using C# instead of JavaScript. It runs in the browser (via WebAssembly) or on the server, so you can write front-end code with the same language you use for back-end logic.

Let's break it down

  • Microsoft framework: a set of tools and libraries created by Microsoft that developers can use to build software.
  • Interactive web pages: websites that respond to user actions without needing to reload the whole page (like clicking a button and seeing new content instantly).
  • C# instead of JavaScript: C# is a programming language often used for desktop and server apps; Blazor lets you use it to write the code that runs in the browser, which is usually written in JavaScript.
  • Runs in the browser (WebAssembly): WebAssembly is a low-level code format that browsers can execute quickly, allowing C# code to run directly in the browser.
  • Runs on the server: In this mode, the browser sends events to the server, the server processes them with C#, and sends back UI updates.

Why does it matter?

Blazor lets .NET developers reuse their existing C# skills to create modern web apps, reducing the need to learn a completely different language (JavaScript) and simplifying code sharing between client and server. This can speed up development, lower maintenance costs, and make it easier for teams already using .NET to expand into web front-ends.

Where is it used?

  • Internal dashboards for enterprises that already run .NET back-ends, allowing a single language stack for both sides.
  • Public-facing web applications like e-commerce sites that want the performance of WebAssembly while keeping business logic in C#.
  • Hybrid mobile or desktop apps built with Blazor Hybrid (e.g., using .NET MAUI) where the same UI code runs on Windows, macOS, iOS, and Android.
  • SaaS platforms that need rapid UI updates and want to share validation and data-model code between server APIs and the browser.

Good things about it

  • Reuse of C# code and .NET libraries across client and server.
  • Strong tooling support in Visual Studio and Visual Studio Code.
  • Two hosting models (WebAssembly and Server) give flexibility for performance or resource constraints.
  • Type-safe, compiled code reduces many runtime errors common in JavaScript.
  • Good integration with existing .NET ecosystem (authentication, EF Core, etc.).

Not-so-good things

  • Larger initial download size for WebAssembly apps, which can affect load time on slow connections.
  • Still a younger ecosystem compared to mature JavaScript frameworks, so fewer third-party UI components and community resources.
  • Server-side mode requires a persistent connection (SignalR), which can be a scalability challenge for very high-traffic sites.
  • Learning curve for developers new to .NET or to the component-based model used by Blazor.