Build a .NET MAUI Blazor Hybrid app with a Blazor Web App

This article shows you how to build a .NET MAUI Blazor Hybrid app with a Blazor Web App that uses a shared user interface via a Razor class library (RCL).

Prerequisites and preliminary steps

For prerequisites and preliminary steps, see Build a .NET MAUI Blazor Hybrid app. We recommend using the .NET MAUI Blazor Hybrid tutorial to set up your local system for .NET MAUI development before using the guidance in this article.

.NET MAUI Blazor Hybrid and Web App sample app

Obtain the sample app named MauiBlazorWeb from the Blazor samples GitHub repository (dotnet/blazor-samples) (.NET 8 or later).

The sample app is a starter solution that contains a .NET MAUI Blazor Hybrid (native, cross-platform) app, a Blazor Web App, and a Razor class library (RCL) that contains the shared UI (Razor components) used by the native and web apps.

Migrating a .NET MAUI Blazor Hybrid solution

Instead of using the sample app, you can migrate an existing .NET MAUI Blazor Hybrid app with the guidance in this section using Visual Studio.

Add new project to the solution with the Blazor Web App project template. Select the following options:

• Project name: Use the solution's name with .Web appended. The examples in this article assume the following naming:
  • Solution: MauiBlazorWeb
  • MAUI project: MauiBlazorWeb.Maui
  • Blazor Web App: MauiBlazorWeb.Web
  • Razor class library (RCL) (added in a later step): MauiBlazorWeb.Shared
• Authentication type: None
• Configure for HTTPS: Selected (enabled)
• Interactive render mode: Server
• Interactivity location: Global
• Sample pages: Unselected (disabled)

The Interactivity location setting to Global is important because MAUI apps always run interactively and throw errors on Razor component pages that explicitly specify a render mode. If you don't use a global render mode, you must implement the approach described in the Use Blazor render modes section after following the guidance in this section. For more information, see BlazorWebView needs a way to enable overriding ResolveComponentForRenderMode (dotnet/aspnetcore #51235).

Add new Razor class library (RCL) project to the solution. The examples in this article assume that the project is named MauiBlazorWeb.Shared. Don't select Support pages and views when you add the project to the solution.

Add project references to the RCL from both MAUI project and the Blazor Web App project.

Move the Components folder and all of its contents from the MAUI project to the RCL. Confirm that the Components folder is deleted from the MAUI project.

Tip

When moving a folder or file in Visual Studio, either use keyboard commands or the shortcut menu by right-clicking for a cut and paste operation. Dragging the folder in Visual Studio only copies from one location to another, which requires an extra step to delete the original.

Move the css folder from the wwwroot folder of the MAUI project to the RCL's wwwroot folder.

Delete the following files from the RCL's wwwroot folder:

• background.png
• exampleJsInterop.js

In the RCL, replace the root _Imports.razor file with the one in the RCL's Components folder, overwriting the existing file in the RCL and deleting the original in the Components folder. After moving the file, open it and rename the last two @using statements to match the RCL's namespace. In the following example, the RCL's namespace is MauiBlazorWeb.Shared:

@using MauiBlazorWeb.Shared
@using MauiBlazorWeb.Shared.Components

In the root of the RCL project, delete the following files:

• Component1.razor
• ExampleJsInterop.cs

In the RCL, open the Components/Routes.razor file and change MauiProgram to Routes:

- <Router AppAssembly="@typeof(MauiProgram).Assembly">
+ <Router AppAssembly="@typeof(Routes).Assembly">

Open the MainPage.xaml file in the MAUI project. Add an xmlns:shared reference to the RCL in the ContentPage attributes. In the following example, the RCL's namespace is MauiBlazorWeb.Shared. Set the correct value for both the clr-namespace and the assembly:

xmlns:shared="clr-namespace:MauiBlazorWeb.Shared;assembly=MauiBlazorWeb.Shared"

Also in the MainPage.xaml file, update the BlazorWebView root component ComponentType from local to shared:

- <RootComponent Selector="#app" ComponentType="{x:Type local:Components.Routes}" />
+ <RootComponent Selector="#app" ComponentType="{x:Type shared:Components.Routes}" />

In the MAUI project, open the wwwroot/index.html file and change stylesheets to point to the RCL's static asset path.

Remove the following lines:

- <link rel="stylesheet" href="css/bootstrap/bootstrap.min.css" />
- <link rel="stylesheet" href="css/app.css" />

Replace the preceding lines with the following markup. In the following example, the RCL's static asset path is _content/MauiBlazorWeb.Shared/:

<link rel="stylesheet" href="_content/MauiBlazorWeb.Shared/css/bootstrap/bootstrap.min.css" />
<link rel="stylesheet" href="_content/MauiBlazorWeb.Shared/css/app.css" />

In the Blazor Web App, open the _Imports.razor file and add the following two @using statements for the RCL. In the following example, the RCL's namespace is MauiBlazorWeb.Shared:

@using MauiBlazorWeb.Shared
@using MauiBlazorWeb.Shared.Components

In the Blazor Web App project, open the App component (Components/App.razor). Remove the app.css stylesheet:

- <link rel="stylesheet" href="app.css" />

Replace the preceding line with the RCL's static asset stylesheet references. In the following example, the RCL's static asset path is _content/MauiBlazorWeb.Shared/:

<link rel="stylesheet" href="_content/MauiBlazorWeb.Shared/css/bootstrap/bootstrap.min.css" />
<link rel="stylesheet" href="_content/MauiBlazorWeb.Shared/css/app.css" />

In the Blazor Web App project, delete the following folder and files:

• Components/Layout folder
• Components/Routes.razor
• Components/Pages/Home.razor
• wwwroot/app.css

Open the Blazor Web App's Program.cs file and add an additional assembly for the RCL to the app. In the following example, the RCL's namespace is MauiBlazorWeb.Shared:

app.MapRazorComponents<App>()
    .AddInteractiveServerRenderMode()
    .AddAdditionalAssemblies(typeof(MauiBlazorWeb.Shared._Imports).Assembly);

Run the MAUI project by selecting the project in Solution Explorer and using Visual Studio's start button.

Run the Blazor Web App project by selecting the Blazor Web App project in Solution Explorer and using Visual Studio's start button with the https build configuration.

If you receive a build error that the RCL's assembly can't be resolved, build the RCL project first. If any MAUI project resource errors occur on build, rebuild the MAUI project to clear the errors.

Use Blazor render modes

Use the guidance in one of the following subsections that matches your app's specifications for applying Blazor render modes for a given interactivity location in the Blazor Web App but ignore the render mode assignments in the MAUI project.

Render mode and interactivity specification subsections:

• Global Server interactivity
• Global Auto or WebAssembly interactivity
• Per-page/component Server interactivity
• Per-page/component Auto interactivity
• Per-page/component WebAssembly interactivity

Global Server interactivity

• Interactive render mode: Server
• Interactivity location: Global
• Solution projects
  • MAUI (MauiBlazorWeb.Maui)
  • Blazor Web App (MauiBlazorWeb.Web)
  • RCL (MauiBlazorWeb.Shared): Contains the shared Razor components without setting render modes in each component.

Project references: MauiBlazorWeb.Maui and MauiBlazorWeb.Web have a project reference to MauiBlazorWeb.Shared.

Global Auto or WebAssembly interactivity

• Interactive render mode: Auto or WebAssembly
• Interactivity location: Global
• Solution projects
  • MAUI (MauiBlazorWeb.Maui)
  • Blazor Web App
    • Server project: MauiBlazorWeb.Web
    • Client project: MauiBlazorWeb.Web.Client
  • RCL (MauiBlazorWeb.Shared): Contains the shared Razor components without setting render modes in each component.

Project references:

• MauiBlazorWeb.Maui, MauiBlazorWeb.Web, and MauiBlazorWeb.Web.Client projects have a project reference to MauiBlazorWeb.Shared.
• MauiBlazorWeb.Web has a project reference to MauiBlazorWeb.Web.Client.

Per-page/component Server interactivity

• Interactive render mode: Server
• Interactivity location: Per-page/component
• Solution projects
  • MAUI (MauiBlazorWeb.Maui): Calls InteractiveRenderSettings.ConfigureBlazorHybridRenderModes in MauiProgram.cs.
  • Blazor Web App (MauiBlazorWeb.Web): Doesn't set an @rendermode directive attribute on the HeadOutlet and Routes components of the App component (Components/App.razor).
  • RCL (MauiBlazorWeb.Shared): Contains the shared Razor components that set the InteractiveServer render mode in each component.

MauiBlazorWeb.Maui and MauiBlazorWeb.Web have a project reference to MauiBlazorWeb.Shared.

Add the following InteractiveRenderSettings class to the RCL. The class properties are used to set component render modes.

The MAUI project is interactive by default, so no action is taken at the project level in the MAUI project other than calling InteractiveRenderSettings.ConfigureBlazorHybridRenderModes.

For the Blazor Web App on the web client, the property values are assigned from RenderMode. When the components are loaded into a BlazorWebView for the MAUI project's native client, the render modes are unassigned (null) because the MAUI project explicitly sets the render mode properties to null when ConfigureBlazorHybridRenderModes is called.

InteractiveRenderSettings.cs:

using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.Components.Web;

namespace MauiBlazorWeb.Shared;

public static class InteractiveRenderSettings
{
    public static IComponentRenderMode? InteractiveServer { get; set; } = 
        RenderMode.InteractiveServer;
    public static IComponentRenderMode? InteractiveAuto { get; set; } = 
        RenderMode.InteractiveAuto;
    public static IComponentRenderMode? InteractiveWebAssembly { get; set; } = 
        RenderMode.InteractiveWebAssembly;

    public static void ConfigureBlazorHybridRenderModes()
    {
        InteractiveServer = null;
        InteractiveAuto = null;
        InteractiveWebAssembly = null;
    }
}

In MauiProgram.CreateMauiApp of MauiProgram.cs, call ConfigureBlazorHybridRenderModes:

InteractiveRenderSettings.ConfigureBlazorHybridRenderModes();

In the _Imports.razor file of the .Shared RCL, replace the @using statement for Microsoft.AspNetCore.Components.Web.RenderMode with an @using statement for InteractiveRenderSettings to make the properties of the InteractiveRenderSettings class available to components:

- @using static Microsoft.AspNetCore.Components.Web.RenderMode
+ @using static InteractiveRenderSettings

Note

The assignment of render modes via the RCL's InteractiveRenderSettings class properties differs from a typical standalone Blazor Web App. In a Blazor Web App, the render modes are normally provided by RenderMode in the Blazor Web App's _Import file.

Per-page/component Auto interactivity

• Interactive render mode: Auto
• Interactivity location: Per-page/component
• Solution projects
  • MAUI (MauiBlazorWeb.Maui): Calls InteractiveRenderSettings.ConfigureBlazorHybridRenderModes in MauiProgram.cs.
  • Blazor Web App
    • Server project: MauiBlazorWeb.Web: Doesn't set an @rendermode directive attribute on the HeadOutlet and Routes components of the App component (Components/App.razor).
    • Client project: MauiBlazorWeb.Web.Client
  • RCL (MauiBlazorWeb.Shared): Contains the shared Razor components that set the InteractiveAuto render mode in each component.

Project references:

• MauiBlazorWeb.Maui, MauiBlazorWeb.Web, and MauiBlazorWeb.Web.Client have a project reference to MauiBlazorWeb.Shared.
• MauiBlazorWeb.Web has a project reference to MauiBlazorWeb.Web.Client.

Add the following InteractiveRenderSettings class is added to the RCL. The class properties are used to set component render modes.

The MAUI project is interactive by default, so no action is taken at the project level in the MAUI project other than calling InteractiveRenderSettings.ConfigureBlazorHybridRenderModes.

For the Blazor Web App on the web client, the property values are assigned from RenderMode. When the components are loaded into a BlazorWebView for the MAUI project's native client, the render modes are unassigned (null) because the MAUI project explicitly sets the render mode properties to null when ConfigureBlazorHybridRenderModes is called.

InteractiveRenderSettings.cs:

using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.Components.Web;

namespace MauiBlazorWeb.Shared;

public static class InteractiveRenderSettings
{
    public static IComponentRenderMode? InteractiveServer { get; set; } = 
        RenderMode.InteractiveServer;
    public static IComponentRenderMode? InteractiveAuto { get; set; } = 
        RenderMode.InteractiveAuto;
    public static IComponentRenderMode? InteractiveWebAssembly { get; set; } = 
        RenderMode.InteractiveWebAssembly;

    public static void ConfigureBlazorHybridRenderModes()
    {
        InteractiveServer = null;
        InteractiveAuto = null;
        InteractiveWebAssembly = null;
    }
}

In MauiProgram.CreateMauiApp of MauiProgram.cs, call ConfigureBlazorHybridRenderModes:

InteractiveRenderSettings.ConfigureBlazorHybridRenderModes();

In the _Imports.razor file of the .Shared RCL, replace the @using statement for Microsoft.AspNetCore.Components.Web.RenderMode with an @using statement for InteractiveRenderSettings to make the properties of the InteractiveRenderSettings class available to components:

- @using static Microsoft.AspNetCore.Components.Web.RenderMode
+ @using static InteractiveRenderSettings

Note

The assignment of render modes via the RCL's InteractiveRenderSettings class properties differs from a typical standalone Blazor Web App. In a Blazor Web App, the render modes are normally provided by RenderMode in the Blazor Web App's _Import file.

Per-page/component WebAssembly interactivity

• Interactive render mode: WebAssembly
• Interactivity location: Per-page/component
• Solution projects
  • MAUI (MauiBlazorWeb.Maui)
  • Blazor Web App
    • Server project: MauiBlazorWeb.Web: Doesn't set an @rendermode directive attribute on the HeadOutlet and Routes components of the App component (Components/App.razor).
    • Client project: MauiBlazorWeb.Web.Client
  • RCLs
    • MauiBlazorWeb.Shared
    • MauiBlazorWeb.Shared.Client: Contains the shared Razor components that set the InteractiveWebAssembly render mode in each component. The .Shared.Client RCL is maintained separately from the .Shared RCL because the app should maintain the components that are required to run on WebAssembly separately from the components that run on server and that stay on the server.

Project references:

• MauiBlazorWeb.Maui and MauiBlazorWeb.Web have project references to MauiBlazorWeb.Shared.
• MauiBlazorWeb.Web has a project reference to MauiBlazorWeb.Web.Client.
• MauiBlazorWeb.Web.Client and MauiBlazorWeb.Shared have a project reference to MauiBlazorWeb.Shared.Client.

Add the following AdditionalAssemblies parameter to the Router component instance for the MauiBlazorWeb.Shared.Client project assembly (via its _Imports file) in the MauiBlazorWeb.Shared project's Routes.razor file:

<Router AppAssembly="@typeof(Routes).Assembly" 
        AdditionalAssemblies="new [] { typeof(MauiBlazorWeb.Shared.Client._Imports).Assembly }">
    <Found Context="routeData">
        <RouteView RouteData="@routeData" DefaultLayout="@typeof(Components.Layout.MainLayout)" />
        <FocusOnNavigate RouteData="@routeData" Selector="h1" />
    </Found>
</Router>

Add the MauiBlazorWeb.Shared.Client project assembly (via its _Imports file) with the following AddAdditionalAssemblies call in the MauiBlazorWeb.Web project's Program.cs file:

app.MapRazorComponents<App>()    
    .AddInteractiveWebAssemblyRenderMode()
    .AddAdditionalAssemblies(typeof(MauiBlazorWeb.Shared._Imports).Assembly)
    .AddAdditionalAssemblies(typeof(MauiBlazorWeb.Shared.Client._Imports).Assembly); 

Add the following InteractiveRenderSettings class is added to the .Shared.Client RCL. The class properties are used to set component render modes for server-based components.

The MAUI project is interactive by default, so no action is taken at the project level in the MAUI project other than calling InteractiveRenderSettings.ConfigureBlazorHybridRenderModes.

For the Blazor Web App on the web client, the property values are assigned from RenderMode. When the components are loaded into a BlazorWebView for the MAUI project's native client, the render modes are unassigned (null) because the MAUI project explicitly sets the render mode properties to null when ConfigureBlazorHybridRenderModes is called.

InteractiveRenderSettings.cs (.Shared.Client RCL):

using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.Components.Web;

namespace MauiBlazorWeb.Shared;

public static class InteractiveRenderSettings
{
    public static IComponentRenderMode? InteractiveServer { get; set; } = 
        RenderMode.InteractiveServer;
    public static IComponentRenderMode? InteractiveAuto { get; set; } = 
        RenderMode.InteractiveAuto;
    public static IComponentRenderMode? InteractiveWebAssembly { get; set; } = 
        RenderMode.InteractiveWebAssembly;

    public static void ConfigureBlazorHybridRenderModes()
    {
        InteractiveServer = null;
        InteractiveAuto = null;
        InteractiveWebAssembly = null;
    }
}

A slightly different version of the InteractiveRenderSettings class is added to the .Shared RCL. In the class added to the .Shared RCL, InteractiveRenderSettings.ConfigureBlazorHybridRenderModes of the .Shared.Client RCL is called. This ensures that the render mode of WebAssembly components rendered on the MAUI client are unassigned (null) because they're interactive by default on the native client.

InteractiveRenderSettings.cs (.Shared RCL):

using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.Components.Web;

namespace MauiBlazorWeb.Shared
{
    public static class InteractiveRenderSettings
    {
        public static IComponentRenderMode? InteractiveServer { get; set; } = 
            RenderMode.InteractiveServer;
        public static IComponentRenderMode? InteractiveAuto { get; set; } = 
            RenderMode.InteractiveAuto;
        public static IComponentRenderMode? InteractiveWebAssembly { get; set; } = 
            RenderMode.InteractiveWebAssembly;

        public static void ConfigureBlazorHybridRenderModes()
        {
            InteractiveServer = null;
            InteractiveAuto = null;
            InteractiveWebAssembly = null;
            MauiBlazorWeb.Shared.Client.InteractiveRenderSettings
                .ConfigureBlazorHybridRenderModes();
        }
    }
}

In MauiProgram.CreateMauiApp of MauiProgram.cs, call ConfigureBlazorHybridRenderModes:

InteractiveRenderSettings.ConfigureBlazorHybridRenderModes();

In the _Imports.razor file of the .Shared.Client RCL, replace the @using statement for Microsoft.AspNetCore.Components.Web.RenderMode with an @using statement for InteractiveRenderSettings to make the properties of the InteractiveRenderSettings class available to components:

- @using static Microsoft.AspNetCore.Components.Web.RenderMode
+ @using static InteractiveRenderSettings

Note

The assignment of render modes via the RCL's InteractiveRenderSettings class properties differs from a typical standalone Blazor Web App. In a Blazor Web App, the render modes are normally provided by RenderMode via in the Blazor Web App's _Import file.

Using interfaces to support different device implementations

The following example demonstrates how to use an interface to call into different implementations across the web app and the native (MAUI) app. The following example creates a component that displays the device form factor. Use the MAUI abstraction layer for native apps and provide an implementation for the web app.

In the Razor class library (RCL), an Interfaces folder contains an IFormFactor interface.

Interfaces/IFormFactor.cs:

namespace MauiBlazorWeb.Shared.Interfaces;

public interface IFormFactor
{
    public string GetFormFactor();
    public string GetPlatform();
}

The following DeviceFormFactor component is present in the RCL's Components folder.

Components/Pages/DeviceFormFactor.razor:

@page "/device-form-factor"
@using MauiBlazorWeb.Shared.Interfaces
@inject IFormFactor FormFactor

<PageTitle>Form Factor</PageTitle>

<h1>Device Form Factor</h1>

<p>You are running on:</p>

<ul>
    <li>Form Factor: @factor</li>
    <li>Platform: @platform</li>
</ul>

<p>
    <em>This component is defined in the MauiBlazorWeb.Shared library.</em>
</p>

@code {
    private string factor => FormFactor.GetFormFactor();
    private string platform => FormFactor.GetPlatform();
}

In the RCL, an entry for the DeviceFormFactor component is part of the navigation menu in the NavMenu component.

In Components/Layout/NavMenu.razor:

<div class="nav-item px-3">
    <NavLink class="nav-link" href="device-form-factor">
        <span class="bi bi-list-nested-nav-menu" aria-hidden="true"></span> Form Factor
    </NavLink>
</div>

The web and native apps contain the implementations for IFormFactor.

In the Blazor Web App, a folder named Services contains the following FormFactor.cs file with the FormFactor implementation for web app use.

Services/FormFactor.cs (MauiBlazorWeb.Web project):

using MauiBlazorWeb.Shared.Interfaces;

namespace MauiBlazorWeb.Web.Services;

public class FormFactor : IFormFactor
{
    public string GetFormFactor() => "Web";

    public string GetPlatform() => Environment.OSVersion.ToString();
}

In the MAUI project, a folder named Services contains the following FormFactor.cs file with the FormFactor implementation for native use. The MAUI abstractions layer is used to write code that works on all native device platforms.

Services/FormFactor.cs (MauiBlazorWeb.Maui project):

using MauiBlazorWeb.Shared.Interfaces;

namespace MauiBlazorWeb.Maui.Services;

public class FormFactor : IFormFactor
{
    public string GetFormFactor() => DeviceInfo.Idiom.ToString();

    public string GetPlatform() =>
        DeviceInfo.Platform.ToString() + " - " + DeviceInfo.VersionString;
}

Dependency injection is used to obtain the implementations of these services.

In the MAUI project, the MauiProgram.cs file has following using statements at the top of the file:

using MauiBlazorWeb.Maui.Services;
using MauiBlazorWeb.Shared.Interfaces;

Immediately before the call to builder.Build(), FormFactor is registered to add device-specific services used by the RCL:

builder.Services.AddSingleton<IFormFactor, FormFactor>();

In the Blazor Web App, the Program file has the following using statements at the top of the file:

using MauiBlazorWeb.Shared.Interfaces;
using MauiBlazorWeb.Web.Services;  

Immediately before the call to builder.Build(), FormFactor is registered to add device-specific services used by the Blazor Web App:

builder.Services.AddScoped<IFormFactor, FormFactor>();

If the solution also targets WebAssembly via a .Web.Client project, an implementation of the preceding API is also required in the .Web.Client project.

You can also use compiler preprocessor directives in your RCL to implement different UI depending on the device the app is running on. For this scenario, the app must multi-target the RCL just like the MAUI app does. For an example, see the BethMassi/BethTimeUntil GitHub repository.

Additional resources

• ASP.NET Core Blazor Hybrid authentication and authorization
• ASP.NET Core Blazor render modes
• Reuse Razor components in ASP.NET Core Blazor Hybrid apps