Most referral-code sites are lists of anonymous strings: you copy one and someone you'll never know gets the reward. RefKings ties every code to a real profile. Search an app like Uber Eats or Revolut, see everyone who shares a code for it, and pick whose to use: a friend, a creator you follow, or whoever explains the offer best. Sharing codes? Get one public page with all of them and see how often each is copied. Free.