title: Unique user id in multi tenant Azure AD apps
body: <p>Do you know the <strong>unique user id</strong> in multi tenant Azure AD apps pattern?</p>
  
  <p>I'm now developing app using <a href="https://developer.microsoft.com/en-us/graph" rel="nofollow noreferrer">Microsoft Graph</a> with Azure AD <a href="https://docs.microsoft.com/en-us/azure/active-directory/develop/active-directory-devhowto-multi-tenant-overview" rel="nofollow noreferrer">multi-tenant application pattern</a>. For identifying each user I want to know the unique id - I'll use it as a key in our own database to save user's data.</p>
  
  <p>In this <a href="https://developer.microsoft.com/en-us/graph/docs/api-reference/v1.0/resources/user#properties" rel="nofollow noreferrer">reference</a>, id parameter in user object is "The unique identifier for the user", but I wonder <strong>is it unique id in each tenant or in all tenant</strong>? It is important thing because my app will use in multi tenant.</p>
  
  <p>FYI:
  If user id is unique only in each tenant, I'll concatenate <a href="https://developer.microsoft.com/en-us/graph/docs/api-reference/v1.0/resources/organization#properties" rel="nofollow noreferrer">organization id</a> and user id for making unique id in all tenant.</p>