The following are a few of the top refer and earn apps for 2021:1. Uber: When a new user signs up with a referral code, the ride-hailing app offers referral bonusesaviatir to both the referrer & the new user. 2. . Airbnb: When a new user books their first reservation through a referral link, the hotel booking website credits both the referrer and the new user. Three. Cash App: For referring friends who register and send money through the peer-to-peer payment app, you can earn cash rewards. 4.