1 Answer. The default rails session storage is CookieStore. This means that all the session data is stored in a cookie rather than in the database anywhere.

What does devise store in session?

Devise stores the logged in user's information in the session. This information is used to authenticate the user for all the requests after the user is logged in using cookies. Though cookie store is the default session store provided by Rails, we use Redis as the session store.

Where are sessions stored in Rails?

Using both of the above concepts I can now tell you that the default session store inside of Rails is CookieStore, which is about 4KB in size.