How to build GitHub sign-in with .NET Core (Blazor Server)

For our new friends:

Logto is an Auth0 alternative designed for modern apps and SaaS products. It offers both Cloud and Open-source services to help you quickly launch your identity and management (IAM) system. Enjoy authentication, authorization, and multi-tenant management all in one.

We recommend starting with a free development tenant on Logto Cloud. This allows you to explore all the features easily.

In this article, we will go through the steps to quickly build the GitHub sign-in experience (user authentication) with .NET Core (Blazor Server) and Logto.

Prerequisites

A running Logto instance. Check out the introduction page to get started.
Basic knowledge of .NET Core (Blazor Server).
A usable GitHub account.

Create an application in Logto

Logto is based on OpenID Connect (OIDC) authentication and OAuth 2.0 authorization. It supports federated identity management across multiple applications, commonly called Single Sign-On (SSO).

To create your Traditional web application, simply follow these steps:

Open the Logto Console. In the "Get started" section, click the "View all" link to open the application frameworks list. Alternatively, you can navigate to Logto Console > Applications, and click the "Create application" button.
In the opening modal, click the "Traditional web" section or filter all the available "Traditional web" frameworks using the quick filter checkboxes on the left. Click the ".Net Core (Blazor Server)" framework card to start creating your application.
Enter the application name, e.g., "Bookstore," and click "Create application".

🎉 Ta-da! You just created your first application in Logto. You'll see a congrats page which includes a detailed integration guide. Follow the guide to see what the experience will be in your application.

Integrate .Net Core (Blazor Server) with Logto

tip:

The following demonstration is built on .NET Core 8.0. The SDK is compatible with .NET 6.0 or higher.
The .NET Core sample projects are available in the GitHub repository.

Installation

Add the NuGet package to your project:

dotnet add package Logto.AspNetCore.Authentication

Add Logto authentication

Open Startup.cs (or Program.cs) and add the following code to register Logto authentication services:

Program.cs
using Logto.AspNetCore.Authentication;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddLogtoAuthentication(options =>
{
  options.Endpoint = builder.Configuration["Logto:Endpoint"]!;
  options.AppId = builder.Configuration["Logto:AppId"]!;
  options.AppSecret = builder.Configuration["Logto:AppSecret"];
});

The AddLogtoAuthentication method will do the following things:

Set the default authentication scheme to LogtoDefaults.CookieScheme.
Set the default challenge scheme to LogtoDefaults.AuthenticationScheme.
Set the default sign-out scheme to LogtoDefaults.AuthenticationScheme.
Add cookie and OpenID Connect authentication handlers to the authentication scheme.

Before we proceed, there are two confusing terms in the .NET Core authentication middleware that we need to clarify:

CallbackPath: The URI that Logto will redirect the user back to after the user has signed in (the "redirect URI" in Logto)
RedirectUri: The URI that will be redirected to after necessary actions have been taken in the Logto authentication middleware.

The sign-in process can be illustrated as follows:

Similarly, .NET Core also has SignedOutCallbackPath and RedirectUri for the sign-out flow.

For the sake of clarity, we'll refer them as follows:

Term we use	.NET Core term
Logto redirect URI	CallbackPath
Logto post sign-out redirect URI	SignedOutCallbackPath
Application redirect URI	RedirectUri

This authentication process follows the OpenID Connect (OIDC) protocol, and Logto enforces strict security measures to protect user sign-in.
If you have multiple apps, you can use the same identity provider (Logto). Once the user signs in to one app, Logto will automatically complete the sign-in process when the user accesses another app.

To learn more about the rationale and benefits of redirect-based sign-in, see Logto sign-in experience explained.

Configure redirect URIs

note:

In the following code snippets, we assume your app is running on http://localhost:3000/.

First, let's configure the Logto redirect URI. Add the following URI to the "Redirect URIs" list in the Logto application details page:

http://localhost:3000/Callback

To configure the Logto post sign-out redirect URI, add the following URI to the "Post sign-out redirect URIs" list in the Logto application details page:

http://localhost:3000/SignedOutCallback

Change the default paths

The Logto redirect URI has a default path of /Callback, and the Logto post sign-out redirect URI has a default path of /SignedOutCallback.

You can leave them as are if there's no special requirement. If you want to change it, you can set the CallbackPath and SignedOutCallbackPath property for LogtoOptions:

Program.cs
builder.Services.AddLogtoAuthentication(options =>
{
  // Other configurations...
  options.CallbackPath = "/Foo";
  options.SignedOutCallbackPath = "/Bar";
});

Remember to update the value in the Logto application details page accordingly.

Add routes

Since Blazor Server uses SignalR to communicate between the server and the client, this means methods that directly manipulate the HTTP context (like issuing challenges or redirects) don't work as expected when called from a Blazor component.

To make it right, we need to explicitly add two endpoints for sign-in and sign-out redirects:

Program.cs
app.MapGet("/SignIn", async context =>
{
    if (!(context.User?.Identity?.IsAuthenticated ?? false))
    {
        await context.ChallengeAsync(new AuthenticationProperties { RedirectUri = "/" });
    } else {
        context.Response.Redirect("/");
    }
});

app.MapGet("/SignOut", async context =>
{
    if (context.User?.Identity?.IsAuthenticated ?? false)
    {
        await context.SignOutAsync(new AuthenticationProperties { RedirectUri = "/" });
    } else {
        context.Response.Redirect("/");
    }
});

Now we can redirect to these endpoints to trigger sign-in and sign-out.

Implement sign-in/sign-out buttons

In the Razor component, add the following code:

Components/Pages/Index.razor
@using Microsoft.AspNetCore.Components.Authorization
@using System.Security.Claims
@inject AuthenticationStateProvider AuthenticationStateProvider
@inject NavigationManager NavigationManager

@* ... *@

<p>Is authenticated: @User.Identity?.IsAuthenticated</p>
@if (User.Identity?.IsAuthenticated == true)
{
    <button @onclick="SignOut">Sign out</button>
}
else
{
    <button @onclick="SignIn">Sign in</button>
}

@* ... *@

@code {
    private ClaimsPrincipal? User { get; set; }

    protected override async Task OnInitializedAsync()
    {
        var authState = await AuthenticationStateProvider.GetAuthenticationStateAsync();
        User = authState.User;
    }

    private void SignIn()
    {
        NavigationManager.NavigateTo("/SignIn", forceLoad: true);
    }

    private void SignOut()
    {
        NavigationManager.NavigateTo("/SignOut", forceLoad: true);
    }
}

Explanation:

The injected AuthenticationStateProvider is used to get the current user's authentication state, and populate the User property.
The SignIn and SignOut methods are used to redirect the user to the sign-in and sign-out endpoints respectively. Since the nature of Blazor Server, we need to use NavigationManager with force load to trigger the redirection.

The page will show the "Sign in" button if the user is not authenticated, and show the "Sign out" button if the user is authenticated.

The `<AuthorizeView />` component

Alternatively, you can use the AuthorizeView component to conditionally render content based on the user's authentication state. This component is useful when you want to show different content to authenticated and unauthenticated users.

In your Razor component, add the following code:

Components/Pages/Index.razor
@using Microsoft.AspNetCore.Components.Authorization

@* ... *@

<AuthorizeView>
    <Authorized>
        <p>Name: @User?.Identity?.Name</p>
        @* Content for authenticated users *@
    </Authorized>
    <NotAuthorized>
        @* Content for unauthenticated users *@
    </NotAuthorized>
</AuthorizeView>

@* ... *@

The AuthorizeView component requires a cascading parameter of type Task<AuthenticationState>. A direct way to get this parameter is to add the <CascadingAuthenticationState> component. However, due to the nature of Blazor Server, we cannot simply add the component to the layout or the root component (it may not work as expected). Instead, we can add the following code to the builder (Program.cs or Startup.cs) to provide the cascading parameter:

Program.cs
builder.Services.AddCascadingAuthenticationState();

Then you can use the AuthorizeView component in every component that needs it.

Checkpoint: Test your application

Now, you can test your application:

Run your application, you will see the sign-in button.
Click the sign-in button, the SDK will init the sign-in process and redirect you to the Logto sign-in page.
After you signed in, you will be redirected back to your application and see the sign-out button.
Click the sign-out button to clear token storage and sign out.

Add GitHub connector

To enable quick sign-in and improve user conversion, connect with .Net Core (Blazor Server) as an identity provider. The Logto social connector helps you establish this connection in minutes by allowing several parameter inputs.

To add a social connector, simply follow these steps:

Navigate to Console > Connectors > Social Connectors.
Click "Add social connector" and select "GitHub".
Follow the README guide and complete required fields and customize settings.

note:

If you are following the in-place Connector guide, you can skip the next section.

Set up GitHub OAuth app

Step 1: Create an OAuth app on GitHub

Before you can use GitHub as an authentication provider, you must create an OAuth App on GitHub to obtain OAuth 2.0 credentials.

Go to GitHub and sign in with your account, or create a new account if needed.
Navigate to Settings > Developer settings > OAuth apps.
Click New OAuth App to register a new application:
- Application name: Enter a descriptive name for your app.
- Homepage URL: Enter your application's homepage URL.
- Authorization callback URL: Copy the Callback URI from your Logto GitHub connector and paste it here. After users sign in with GitHub, they'll be redirected here with an authorization code that Logto uses to complete authentication.
- Application description: (Optional) Add a brief description of your app.
Click Register application to create the OAuth App.

note:

We suggest not checking the box for Enable Device Flow, as users who sign in with GitHub on mobile devices would need to confirm the initial sign-in action in the GitHub mobile app. Many GitHub users do not install the GitHub mobile app on their phones, which could block the sign-in flow. Only enable this if you expect end-users to confirm their sign-in flow through the GitHub mobile app. See details about device flow.

For more details on setting up GitHub OAuth Apps, see Creating an OAuth App.

Step 2: Configure your Logto connector

After creating the OAuth app in GitHub, you'll be redirected to a details page where you can copy the Client ID and generate a Client secret.

Copy the Client ID from your GitHub OAuth app and paste it into the clientId field in Logto.
Click Generate a new client secret in GitHub to create a new secret, then copy and paste it into the clientSecret field in Logto.
Click Save and Done in Logto to connect your identity system with GitHub.

warning:

Keep your Client secret secure and never expose it in client-side code. GitHub client secrets cannot be recovered if lost - you'll need to generate a new one.

Step 3: Configure scopes (Optional)

Scopes define the permissions your app requests from users and control which data your app can access from their GitHub accounts.

Use the Scopes field in Logto to request extra permissions from GitHub. Choose one of the following approaches based on your needs:

Option 1: No extra API scopes needed

Leave the Scopes field in your Logto GitHub connector blank.
The default scope read:user will be requested to ensure Logto can get basic user info (e.g., email, name, avatar) properly.

Browse all available GitHub scopes for OAuth apps and add only the scopes your app needs.
Enter all desired scopes in the Scopes field, separated by spaces.
Any scopes you list here override the defaults, so always include the authentication scope: read:user.
Common additional scopes include:
- repo: Full control of private repositories
- public_repo: Access to public repositories
- user:email: Access to user email addresses
- notifications: Access to notifications
Ensure all scopes are spelled correctly and valid. An incorrect or unsupported scope will result in an "Invalid scope" error from GitHub.

Option 3: Request incremental scopes later

After the user signs in, you can request additional scopes on demand by reinitiating a federated social authorization flow and updating users' stored token set.
These additional scopes do not need to be filled in the Scopes field in your Logto GitHub connector, and can be achieved through Logto's Social Verification API.

By following these steps, your Logto GitHub connector requests exactly the permissions your app needs - no more, no less.

tip:

If your app requests these scopes to access the GitHub API and perform actions, make sure to enable Store tokens for persistent API access in Logto GitHub connector. See the next section for details.

Step 4: General settings

Here are some general settings that won't block the connection to GitHub but may affect the end-user authentication experience.

Sync profile information

In the GitHub connector, you can set the policy for syncing profile information, such as user names and avatars. Choose from:

Only sync at sign-up: Profile info is fetched once when the user first signs in.
Always sync at sign-in: Profile info is updated every time the user signs in.

Store tokens to access GitHub APIs (Optional)

If you want to access GitHub APIs and perform actions with user authorization (whether via social sign-in or account linking), Logto needs to get specific API scopes and store tokens.

Add the required scopes following the instructions above.
Enable Store tokens for persistent API access in the Logto GitHub connector. Logto will securely store GitHub access tokens in the Secret Vault.

note:

When using a GitHub OAuth App as described in this tutorial, you cannot get a refresh token from GitHub because its access token does not expire unless the user manually revokes it. Therefore, you do not need to add offline_access in the Scopes field — doing so may cause an error.

If you want the access token to expire or use refresh tokens, consider integrating with a GitHub App instead. Learn about the differences between GitHub Apps and OAuth Apps.

Step 5: Test your integration (Optional)

Before going live, test your GitHub integration:

Use the connector in a Logto development tenant.
Verify that users can sign in with GitHub.
Check that the correct scopes are being requested.
Test API calls if you're storing tokens.

GitHub OAuth Apps work with any GitHub user account immediately - there's no need for test users or app approval like some other platforms.

Save your configuration

Double check you have filled out necessary values in the Logto connector configuration area. Click "Save and Done" (or "Save changes") and the GitHub connector should be available now.

Once you create a social connector successfully, you can enable it as a "Continue with GitHub" button in Sign-in Experience.

Navigate to Console > Sign-in experience > Sign-up and sign-in.
(Optional) Choose "Not applicable" for sign-up identifier if you need social login only.
Add configured GitHub connector to the "Social sign-in" section.

Testing and Validation

Return to your .NET Core (Blazor Server) app. You should now be able to sign in with GitHub. Enjoy!

Create an application in Logto​

Integrate .Net Core (Blazor Server) with Logto​

Installation​

Add Logto authentication​

Sign-in and sign-out flows​

Regarding redirect-based sign-in​

Configure redirect URIs​

Change the default paths​

Add routes​

Implement sign-in/sign-out buttons​

The <AuthorizeView /> component​

Checkpoint: Test your application​

Add GitHub connector​

Set up GitHub OAuth app​

Step 1: Create an OAuth app on GitHub​

Step 2: Configure your Logto connector​

Step 3: Configure scopes (Optional)​

Option 1: No extra API scopes needed​

Option 2: Request additional scopes at sign-in​

Option 3: Request incremental scopes later​

Step 4: General settings​

Sync profile information​

Store tokens to access GitHub APIs (Optional)​

Step 5: Test your integration (Optional)​

Save your configuration​

Enable GitHub connector in Sign-in Experience​

Testing and Validation​

Further readings​

Create an application in Logto

Integrate .Net Core (Blazor Server) with Logto

Installation

Add Logto authentication

Sign-in and sign-out flows

Regarding redirect-based sign-in

Configure redirect URIs

Change the default paths

Add routes

Implement sign-in/sign-out buttons

The `<AuthorizeView />` component

Checkpoint: Test your application

Add GitHub connector

Set up GitHub OAuth app

Step 1: Create an OAuth app on GitHub

Step 2: Configure your Logto connector

Step 3: Configure scopes (Optional)

Option 1: No extra API scopes needed

Option 2: Request additional scopes at sign-in

Option 3: Request incremental scopes later

Step 4: General settings

Sync profile information

Store tokens to access GitHub APIs (Optional)

Step 5: Test your integration (Optional)

Save your configuration

Enable GitHub connector in Sign-in Experience

Testing and Validation

Further readings