If you are wondering is signing in with your social media account is indeed secure, this should help you use it with confidence as it saves you from the hassle of remembering multiple usernames and passwords.
Please note that
We DO NOT have access to any of your personal information except for that for what we seek your permission for or enforced by law. During the sign up process, we shall ONLY get the following information prefilled from your social media account – Name , Email Address . Apart from this we do not get access to any information to your personal details such as your friends' email, contact details or any other information.
We DO NOT POST anything on your wall/ account or on your behalf in any manner, unless you grant us an express permission. This permission is never included in the Permission we ask for to grant you access via your social media account – and even all social media platforms do not grant any application/website using their sign up assistance for this permission during signup process, and this must be sought separately.
Please refer the following links from a few social media platforms which support signing in with social media account is 100% secure