Looks like it uses the same api as Rapportive based on the permissions it asks for when installing.
var LOGIN_URL = 'https://rapportive.com/login_status';
var LOOKUP_URL = 'https://profiles.rapportive.com/contacts/email/';
var API_HOST = '104.131.218.68';
var API_URL = 'http://'+API_HOST+'/api/profiles';