In order to provide free products, for companies, they must resort to a new money-making model. Even open source software, they need to get money through personal or corporate donations. At present, under the premise of free products, the most common ways to make money among developers are as follows:

advertising and sponsorship: generally speaking, doing content and doing online platforms is to make money through this method. Of course, many other products are also like this. Think about twitter, pandora, words with friends and the websites you are currently browsing. In many cases, companies offer paid versions to consumers, and there are no ads in these paid versions. But if the user is willing, they can enjoy the service without paying.

Hosting and storage: for many saas products, users don't need to spend money on features, but they need to pay for bandwidth, disk space, and more. In the case of wordpress, its products are free, but it charges a few dollars a month to bloggers who put their own blogs on their servers and have their own custom domain names. And enterprise products that pay for people, such as salesforce and mailchimp, are charged based on data storage and server usage time, not their own tools.

Transaction processing: products like etsy and paypal tend to offer free tools in the trading market, on the one hand to increase the liquidity of their services, and on the other hand, because they can be easily charged through transactions. This model has even been used in kind: square has offered its credit card readers to users free of charge to expand its user base and then charge for it through its huge transaction volume.

Service: if people can enjoy the red carpet treatment, they are still willing to pay. Free products typically drive consumption by providing users with a paid "upsell" service. For example, although the app itself is free, open source developers typically charge customers for their technical support.

Cross-selling or selling other products: in general, many companies offer a feature-based free product and then induce potential users to purchase their more profitable paid products, the so-called freemium model. At the top of the product chain are products that cannot be profited by other means, and the products under the chain will become free to support the above paid products.

Shortcuts for users: this method means providing apps for users for free, but if they want to cheat or jump in the queue, they need to pay. Social games such as farmville are an interesting example of this model: in-app payments become a good way for users to evade patience.