Service ID

Enable Sign in with Apple on your website or web app.

Use Sign in with Apple to let your users sign in to your app’s accompanying website with their Apple ID. To configure web authentication, you must create a Services ID and associate your website to an existing primary iOS, macOS, tvOS, or watchOS App ID enabled for Sign in with Apple.

1. Create Service ID

2. Find Service ID using Apple Developer Portal

Create Service ID

1. In Certificates, Identifiers & Profiles, click Identifiers in the sidebar, then click the add button (+) on the top left.

2. Select Services ID, then click Continue.

   

   Select Services ID, then click Continue
3. Enter the Services ID description and provide a unique identifier.

   

   Use unique identifier not Bundle ID of any app
4. Register the Services ID and select it from the list to start configuration.

5. Select Sign in with Apple, then click Configure.

6. Select your app from the list of primary App IDs related to your website in the modal that appears.

7. Under Website URLs, provide api.codemash.io in the Somains and Subdomains section, and set https://api.codemash.io/auth/apple as Return URLs.

   
8. Click Done to store your configuration.

9. Click Continue.

10. Review the configuration, then click Save.

Find Service ID using Apple Developer Portal

1. Go to the Apple Developer Portal and sign in with your Apple ID.

2. From the home page, click on the "Identifiers" link.

   

   Press "Identifiers" link
3. You will see a list of all registered identifiers to your account. Please ensure that the "Services IDs" filter is selected on the right side of the screen.

   
4. Filter and find services by description or identifier.

5. The identifier is your Service ID

Here is the original Apple documentation - https://developer.apple.com/help/account/configure-app-capabilities/configure-sign-in-with-apple-for-the-web