Rakuten: Formerly known as Ebates, Rakuten is a cash back app that rewards users for shopping at over 2,500 online retailers. Customers can receive their earfun slotsnings as a check or via PayPal when they earn cash back on their purchases. Five. Acorns: Acorns is an investment app that allows users to invest their spare change from everyday purchases into a diversified portfolio. Also, customers who make purchases from Acorns' partner brands can receive cash back rewards.