How to build GitHub (GitHub App) 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 (GitHub App) 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 (GitHub App) 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

ヒント:

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

注記:

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 (GitHub App) 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 (GitHub App)".
Follow the README guide and complete required fields and customize settings.

注記:

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

Set up GitHub (GitHub App)

Step 1: Create a GitHub App

Before you can use GitHub as an authentication provider, you must create a GitHub 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 > GitHub Apps.
Click New GitHub App to register a new application:
- GitHub App name: Enter a unique name for your app. The name cannot be longer than 34 characters and must be unique across GitHub.
- Homepage URL: Enter your application's homepage URL.
- Callback URL: Copy the Callback URI from your Logto GitHub connector and paste it here. You can add multiple callback URLs if needed. After users sign in with GitHub, they'll be redirected here with an authorization code that Logto uses to complete authentication.
- Expire user authorization tokens: Keep this checked (recommended). This enables token expiration and refresh tokens for enhanced security.
- Request user authorization (OAuth) during installation: Optionally check this to prompt users to authorize your app during installation.
- Webhook: Uncheck Active if you don't need webhook events. For authentication-only use cases, webhooks are typically not required.
Under Permissions, configure the permissions your app needs (see Step 2 below for details).
Under Where can this GitHub App be installed?, select Any account if you want users from any GitHub account to use your app for authentication.
Click Create GitHub App to create the GitHub App.

注記:

Unlike OAuth Apps, GitHub Apps use fine-grained permissions instead of broad scopes. You configure permissions in the GitHub dashboard during app creation, and users grant access to specific repositories during authorization.

For more details on setting up GitHub Apps, see Registering a GitHub App.

Step 2: Configure permissions in GitHub

GitHub Apps use fine-grained permissions instead of OAuth scopes. You must configure permissions in the GitHub dashboard when creating or editing your GitHub App. These permissions determine what data your app can access.

Understanding GitHub App permissions

Permissions are categorized into three types:

Repository permissions: Access to repository-level resources (code, issues, pull requests, etc.)
Organization permissions: Access to organization-level resources (members, teams, projects, etc.)
Account permissions: Access to user account data (email, profile, followers, etc.)

For each permission, you can select:

No access: The app cannot access this resource
Read-only: The app can read but not modify this resource
Read & write: The app can read and modify this resource

Recommended permissions for authentication

For basic "Sign in with GitHub" functionality, configure these minimum Account permissions:

Permission	Access level	Purpose
Email addresses	Read-only	Get user's email address for account creation

ヒント:

GitHub Apps have implicit access to read public profile information when acting on behalf of a user. You don't need to explicitly request permission for basic profile data like username, avatar, and public profile URL.

Additional permissions for API access

If your application needs to access GitHub APIs beyond authentication, add the corresponding permissions in the GitHub dashboard. Here are some common examples:

Permission type	Permission	Access level	Use case
Repository	Contents	Read-only / Read & write	Access repository files and code
Repository	Issues	Read & write	Create and manage issues
Repository	Pull requests	Read & write	Create and manage pull requests
Repository	Metadata	Read-only	Access repository metadata (required for many operations)
Organization	Members	Read-only	List organization members
Account	Followers	Read-only	Access user's followers and following

This is not an exhaustive list — GitHub Apps support many more fine-grained permissions. See Permissions required for GitHub Apps for the complete list.

Key difference from OAuth Apps:

Unlike OAuth Apps where you configure scopes in the Logto connector, GitHub App permissions are managed entirely in the GitHub dashboard. You can leave the Scope field empty in your Logto GitHub connector — it's not needed because GitHub Apps don't use traditional OAuth scopes.

Simply configure the permissions you need in GitHub, and users will be prompted to grant access during authorization.

Step 3: Configure your Logto connector

After creating the GitHub App, you'll be redirected to its settings page where you can obtain the credentials.

On your GitHub App's settings page, copy the Client ID and paste it into the clientId field in Logto.
Under Client secrets, click Generate a new client secret. Copy the generated secret and paste it into the clientSecret field in Logto.
Click Save and Done in Logto to connect your identity system with GitHub.

警告:

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.

注記:

The Client ID for a GitHub App is different from the App ID. Make sure to use the Client ID (shown as "Client ID" on the settings page), not the App ID.

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 configure how profile information is synced from GitHub user info to the Logto user profile, including name, avatar, and email. Choose from the following options:

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), enable token storage in Logto:

Configure the required permissions in your GitHub App settings (Step 2).
Enable Store tokens for persistent API access in the Logto GitHub connector. Logto will securely store both the access token and refresh token in the Secret Vault.

注記:

Since GitHub Apps always issue refresh tokens, Logto stores both tokens automatically. The access token expires after 8 hours, but Logto can use the refresh token to obtain new access tokens, ensuring uninterrupted API access for up to 6 months.

Step 5: Test your integration (Optional)

Before going live, test your GitHub App integration:

Use the connector in a Logto development tenant.
Verify that users can sign in with GitHub.
Check that users are prompted for the correct permissions during authorization.
If you enabled token storage, verify that access tokens (and refresh tokens) are stored correctly.
Test API calls using the stored tokens to ensure permissions are working as expected.

GitHub Apps work with any GitHub user account immediately - there's no need for test users or app approval like some other platforms. However, if your app is installed on an organization, organization owners may need to approve the installation.

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 (GitHub App) connector should be available now.

Once you create a social connector successfully, you can enable it as a "Continue with GitHub (GitHub App)" 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 (GitHub App) 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 (GitHub App). 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 (GitHub App) connector​

Set up GitHub (GitHub App)​

Step 1: Create a GitHub App​

Step 2: Configure permissions in GitHub​

Understanding GitHub App permissions​

Recommended permissions for authentication​

Additional permissions for API access​

Step 3: Configure your Logto connector​

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 (GitHub App) connector in Sign-in Experience​

Testing and Validation​

Further readings​