title: SSO integration for SPA that runs on premise(intranet), not in a public domain
body: <p>I am building a web application where development teams can install and use inside their companies. I am exploring the possibility of adding SSO support with Github since it is very convenient for developers.</p>
  
  <p>In Github API, Auth0, Google etc. you need to specify Callback URLs.</p>
  
  <p>The problem is that since everybody can deploy an instance of my application they can host it under any valid domain or just use a local ip address. So the Callback URLs cannot be predefined.</p>
  
  <p>One option is to instruct people to deploy the app under certain local domains/subdomains. However, I don't think this is a good solution.</p>
  
  <p>Do you know any other options that might solve my problem?</p>
  
  <p>Is SSO only suitable for apps that run under global(already known) domains?</p>