Blazor is a server-side rendered (Server) or client-side rendered (WASM) framework for web apps. Blazor does not use a request/response model.


  • Create UIs in combination of HTML and C# instead of JavaScript
  • Share server-side and client-side app logic
  • Render UI as HTML and CSS
  • Integrate with Docker
  • Build hybrid desktop & mobile apps

Blazor apps are based on Razor components—an element of UI (like a page, dialog, or form).


  • are C# classes
  • render UI, handle user events
  • written as a .razor file (Razor components; informally, Blazor components)
  • NOT built around request/response model (like Razor Pages & MVC)


<div class="card" style="width:22rem">
    <div class="card-body">
        <h3 class="card-title">@Title</h3>
        <p class="card-text">@ChildContent</p>
        <button @onclick="OnYes">Yes!</button>
@code {
    public RenderFragment? ChildContent { get; set; } // text of the dialog

    public string? Title { get; set; } // title of the dialog

    private void OnYes() // triggered by the button's onclick event
   // write's to the browser's console
        Console.WriteLine("Write to the console in C#! 'Yes' button selected.");


@page "/"

<h1>Hello, world!</h1>

    Welcome to your new app.

<Dialog Title="Learn More"> <!-- uses the previously-defined Dialog component --> 
    Do you want to <i>learn more</i> about Blazor? <!-- sets the Dialog component's ChildContent (text) -->


Visual Studio / dotnet new templates

  • Blazor Server App (blazorserver) template — includes demonstration code and Bootstrap
  • Blazor Server App Empty (blazorserver-empty) template — no demo code, no Bootstrap
  • Blazor WASM (blazorwasm) template — includes demonstration code and Bootstrap
  • Blazor WASM Empty (blazorwasm-empty) template — no demo code, no Bootstrap
  • ASP.NET Core Hosted checkbox — check for a hosted Blazor WASM app
    • The startup project is in the Server project

.NET WebAssembly build tools

Based on Emscripten, a compiler toolchain for the web platform. To install, either:

  • Visual Studio installer > Additional Components > .NET WebAssembly build tools
  • dotnet workload install wasm-tools Note: .NET 7 build tools (installed above) are incompatible with .NET 6. To use the .NET 6 build tools:
    dotnet workload install wasm-tools-net6

When AOT compilation is used, SIMD is supported except for Apple Safari. To enable this:


To enable WASM exception handling: