So you will have to do the following: User visits siteA -> a session is missing -> redirect user to auth portal (that uses supertokens) -> if a session exists in the auth portal -> create a one time token and send it back to siteA -> siteA uses that one time token to query auth portal's backend to verify the token -> if the token is valid, siteA creates a session and the user is logged in. Now the logic for creating that one time use token and going about verifying it etc.. is something we don't have yet.

If you want, we can help out here, but we can chat about it separately since this is essentially asking us about consultancy services. If you can email this to rishabh@supertokens.com, we can chat about the pricing for that on email.

I have calendly link of rishabh

and I arranging a meeting

Let me discuss it with my seniors too sir

You can book a call here: https://supertokens.com/call-user