Razor vs Blazor: What Is the Key Difference?

Razor is a popular template markup syntax for .NET. In contrast, Blazor (Browser + Razor) is a .NET based web framework which can run on the client using WebAssembly or running on the server via SignalR.

To give an example, Razor is the syntax you use when creating web apps with ASP.NET, which you’ve probably seen before:

<h1>
    Hello @Model.FirstName
</h1>

Razor takes care of rendering your HTML based on the data in your model, while also supporting various conditionals and loops.

On the other hand, Blazor is a technology similar to ASP.NET Core and ASP.NET MVC in that:

• It powers web applications.
• It uses Razor as its template syntax for the creation of UI.

A common misconception is that Blazor uses Razor. This is further exacerbated by two other similar terms—Blazor UI components and Razor components. Those are widely used interchangeably but the correct terminology is Razor Component. A component is the combination of markup (written in HTML) and logic (in C#) in a single Razor file (with the .cshtml extension).

Here are some considerations to help you make the decision between Blazor and Razor:

When we recommend choosing Razor:

• Server-Side Rendering: If your application primarily requires server-side rendering and you're comfortable with traditional web development approaches, Razor might be a suitable choice. It's well-suited for generating dynamic HTML content on the server and delivering it to the client.
• Existing ASP.NET MVC/Core Project: If you're already working with ASP.NET MVC or ASP.NET Core MVC for server-side rendering and you don't need complex client-side interactivity, sticking with Razor for additional pages or components can be a seamless integration.
• Minimal JavaScript/CSS Interactivity: If your project doesn't require extensive client-side interactivity or dynamic UI updates, Razor can suffice for rendering static or minimally interactive web pages.

When we recommend choosing Blazor:

• Rich Client-Side Interactivity: If you need to build a single-page application (SPA) or a highly interactive web application with rich user interfaces, Blazor is a compelling choice. It allows you to write C# code for client-side logic and UI components, providing a more cohesive development experience.
• Full-Stack .NET Development: If you prefer a full-stack .NET solution where you can use C# for both client-side and server-side development, Blazor offers that capability. You can share code and logic between the client and server, reducing duplication and improving maintainability.
• WebAssembly or Server-Side Execution: Depending on your performance and deployment requirements, you can choose between client-side Blazor (Blazor WebAssembly) for running in the browser using WebAssembly or server-side Blazor for running on the server. Consider factors such as browser compatibility, performance and scalability.
• Component-Based Architecture: If you prefer a component-based architecture like modern JavaScript frameworks, Blazor provides that paradigm. You can create reusable UI components and compose them to build complex user interfaces efficiently.