Hi Scot, We are facing similar issue with keyclaok but would prefer to have the realm resolution implemented in keycloak (not like Kevin suggests on client side). Can you maybe share your experience and the approach you finally implemented? Best regards, Marian -----Original Message----- Hi Scott, Wouldn't it be much easier to implement this "proxy" logic in the mobile app itself? Adding a new layer in your infrastructure could mean another single point of failure and doesn't add much value to it either. Of course, you can write some logic by modifying Keycloak but it could rejected by the community and then you'd have to main your logic in Keycloak yourself. It could break anytime Keycloak has another update and Keycloak is updated frequently. I'd honestly stick by implementing this behavior in your client. Before you redirect your user to the login page or pass his credentials to the Keycloak instance, validate the email and direct the user to the proper realm then. This way you'd have to maintain only a small part of your mobile app and doesn't contain the complexity by maintaining another component in your infrastructure. I hope this will give you some thoughts :-) ! Kind regards, Kevin -----Original Message----- From: keycloak-user-bounces at lists.jboss.org<https://lists.jboss.org/mailman/listinfo/keycloak-user... [mailto:keycloak-user-bounces at lists.jboss.org<https://lists.jboss.org/mailman/listinfo/keycloak-user...] On Behalf Of Scott Hezzell Sent: Tuesday, November 28, 2017 1:40 PM To: keycloak-user at lists.jboss.org<https://lists.jboss.org/mailman/listinfo/keycloak-user... Subject: [keycloak-user] Keycloak realm detection from email domain Hi I am building a multi-tenant mobile application that uses keycloak as a SSO server. We will pre-load users in keycloak using their email address as their username with a separate realm for each tenant. When a user logs into the mobile app I need to detect the realm from a user's email domain and redirect to the appropriate authorisation end point for the realm. Has anyone faced a similar problem? My thoughts at the moment is to build a proxy api that the mobile application redirects to that prompts the user for their email address, look up the configured tenant form the email domain and redirects to the appropriate realm's login page passing the mobile app credentials it passes to the proxy api and the entered user email as a login_hint. Can anyone see any issues with this approach? Or a suggest a better approach? Thanks Scott