I could not find any documentation on what ‘extraParameters’ Auth0Client.LoginAsync accepts as arguments. However, the Auth0OidcClient library is just a wrapper for the IdentityModel.OidcClient2 library. If you trace the source code it brings you to this AuthorizeClient class. Search for the method ‘CreateAuthorizeParameters’ to see what parameters are accepted. The only thing I do not understand is why this method accepts ‘audience’ as a parameter as it is not listed in this method from what I can see.