Auth0 only validate the token for web application

There is a rigid requirement from client:

  1. We are having a gateway web application that performs auth0 authentication.
  2. based on the claims returned by auth0 this gateway app then redirects user to either admin web app (MVC) or user web app (React).
  3. this 2nd level web app should only validate JWT token and if its invalid app should redirect user back to gateway application.

I am having problem with step (3). i.e. how to only validate the token? and redirect user to gateway application instead of Auth0.