Simple question is there a way to know session expiry timestamp/date? Or do I need to count manually by adding timeout (100 days if default) when session is created ?

There should be a function in the session object called

getSessionInformation()

. That should contain the expiry

Session object as in this?

import Session from "supertokens-node/recipe/session";

If you use the Session recipe's static funciton, then you have to pass it a session handle and you can get info about that session. If you verify a session in an API, then the

req.session

object contains that function to return info about the current session.