Cloud authentication with Azure Active Directory B2C in ASP.NET Core

By Cam Soper

Azure Active Directory B2C (Azure AD B2C) is a cloud identity management solution for web and mobile apps. The service provides authentication for apps hosted in the cloud and on-premises. Authentication types include individual accounts, social network accounts, and federated enterprise accounts. Additionally, Azure AD B2C can provide multi-factor authentication with minimal configuration.


Azure Active Directory (Azure AD) Azure AD B2C are separate product offerings. An Azure AD tenant represents an organization, while an Azure AD B2C tenant represents a collection of identities to be used with relying party applications. To learn more, see Azure AD B2C: Frequently asked questions (FAQ).

In this tutorial, learn how to:

  • Create an Azure Active Directory B2C tenant
  • Register an app in Azure AD B2C
  • Use Visual Studio to create an ASP.NET Core web app configured to use the Azure AD B2C tenant for authentication
  • Configure policies controlling the behavior of the Azure AD B2C tenant


The following are required for this walkthrough:

Create the Azure Active Directory B2C tenant

Create an Azure Active Directory B2C tenant as described in the documentation. When prompted, associating the tenant with an Azure subscription is optional for this tutorial.

Register the app in Azure AD B2C

In the newly created Azure AD B2C tenant, register your app using the steps in the documentation under the Register a web app section. Stop at the Create a web app client secret section. A client secret isn't required for this tutorial.

Use the following values:

Setting Value Notes
Name <app name> Enter a Name for the app that describes your app to consumers.
Include web app / web API Yes
Allow implicit flow Yes
Reply URL https://localhost:44300 Reply URLs are endpoints where Azure AD B2C returns any tokens that your app requests. Visual Studio provides the Reply URL to use. For now, enter https://localhost:44300 to complete the form.
App ID URI Leave blank Not required for this tutorial.
Include native client No


If setting up a non-localhost Reply URL, be aware of the constraints on what is allowed in the Reply URL list.

After the app is registered, the list of apps in the tenant is displayed. Select the app that was just registered. Select the Copy icon to the right of the Application ID field to copy it to the clipboard.

Nothing more can be configured in the Azure AD B2C tenant at this time, but leave the browser window open. There is more configuration after the ASP.NET Core app is created.

Create an ASP.NET Core app in Visual Studio 2017

The Visual Studio Web Application template can be configured to use the Azure AD B2C tenant for authentication.

In Visual Studio:

  1. Create a new ASP.NET Core Web Application.
  2. Select Web Application from the list of templates.
  3. Select the Change Authentication button.

    Change Authentication Button

  4. In the Change Authentication dialog, select Individual User Accounts, and then select Connect to an existing user store in the cloud in the dropdown.

    Change Authentication Dialog

  5. Complete the form with the following values:

    Setting Value
    Domain Name <the domain name of your B2C tenant>
    Application ID <paste the Application ID from the clipboard>
    Callback Path <use the default value>
    Sign-up or sign-in policy B2C_1_SiUpIn
    Reset password policy B2C_1_SSPR
    Edit profile policy <leave blank>

    Select the Copy link next to Reply URI to copy the Reply URI to the clipboard. Select OK to close the Change Authentication dialog. Select OK to create the web app.

Finish the B2C app registration

Return to the browser window with the B2C app properties still open. Change the temporary Reply URL specified earlier to the value copied from Visual Studio. Select Save at the top of the window.


If you didn't copy the Reply URL, use the SSL address from the Debug tab in the web project properties, and append the CallbackPath value from appsettings.json.

Configure policies

Use the steps in the Azure AD B2C documentation to create a sign-up or sign-in policy, and then create a password reset policy. Use the example values provided in the documentation for Identity providers, Sign-up attributes, and Application claims. Using the Run now button to test the policies as described in the documentation is optional.


Ensure the policy names are exactly as described in the documentation, as those policies were used in the Change Authentication dialog in Visual Studio. The policy names can be verified in appsettings.json.

Run the app

In Visual Studio, press F5 to build and run the app. After the web app launches, select Sign in.

Sign into the app

The browser redirects to the Azure AD B2C tenant. Sign in with an existing account (if one was created testing the policies) or select Sign up now to create a new account. The Forgot your password? link is used to reset a forgotten password.

Azure AD B2C login

After successfully signing in, the browser redirects to the web app.


Next steps

In this tutorial, you learned how to:

  • Create an Azure Active Directory B2C tenant
  • Register an app in Azure AD B2C
  • Use Visual Studio to create an ASP.NET Core Web Application configured to use the Azure AD B2C tenant for authentication
  • Configure policies controlling the behavior of the Azure AD B2C tenant

Now that the ASP.NET Core app is configured to use Azure AD B2C for authentication, the Authorize attribute can be used to secure your app. Continue developing your app by learning to: