Robinhood: Users who refer friends who sign up and link their bank account will receive a free stock through the referral program offered by the invteem pattiesting app. 5. Rakuten: The cashback shopping app has a referral program that pays out cash bonuses to users who recommend friends who use the app to make eligible purchases. These are just a few instances of refer & earn apps, which give users or customers incentives for referring other users.