I have a private Google site which has been set up to only share with certain email addresses. Those email addresses are from different providers, such as hotmail, yahoo, etc. When users try to access the site, they will be asked to login with their email and Google Account password. If they don't haven't created Google Account for their email, then they will be asked to do so. However I don't want to force them to create one. I want to use the Google Identity Toolkit which allow they to login just with their own email and email's password. I want it to work like this: when users access the site, they will see a sign in screen like ([url removed, login to view]), then they click their provider's icon and go to their provider website and login with their email and password, once they login, then will be redirect back to my site and now allow to browse the site. I hope there is a no-code or little-code way to integrate this two products together since both are Google's.