They make their money in varying forms, and the one which you are probably most aware of is advertisement. As you will have seen with most of these, they have you watch a video before being able to earn rewards.  There are also in-app purchases, and these can take the form of products or services of their own, or ones that are affiliated where they make a commission for every time someone makes a purchase after following links on their pages.    Some of these apps offer subscription fees, particularly for the premium versions, and at other times, you have to spend a little bit of money, either in the app or at an affiliate, before you can gain your reward or cashback.