There are some public information about a facebook profile which any other person with facebook account can easily see by typing that profile URL address in address bar. How can we access that information through Graph API without access token. because i have signed up for facebook developer account this means I have facebook account and i can see that information (which is availble publicly) by login in from my account. Does facebook allows facebook developer to access that info from api with out any access token. e.g home town, birthday, Studied at, Friends (if made public) etc of any facebook profile. Kindly help me in this if someone knows.
Just because something is publicly available via fb dot com doesn't mean it is via the API, too. You need to request public_profile permission from the user, otherwise you cannot access that data via the API. To access the user's birthday (if available) it requires user_birthday permission.
See: https://developers.facebook.com/docs/facebook-login/permissions