MainApp Referral Code, Invitation Code & Sign up Bonus: MainApp App is an app where you can earn by doing various task from your phone or smart device. Tasks include surveys, daily check-ins, watch videos, referring friends, rating the app and more... For the tasks you complete you will earn points and with the points you can cash out for gift cards. Click here for more ways to earn! MainApp App Refer A Friend Bonus Earn extra points by referring your friends to MainApp App. To refer friends send your friend your personal referral code. When they download the app have your friend enter your referral code when asked. Share your MainApp referral code: If you would like to share your MainApp App referral code post it in the comment box below for others to use.