The cost of building a video chat app depends on a number of factors. First, we have to consider for which platforms you are building the app. For instance, if you are building an app for iOS devices, you have to pay a considerable amount to get it published. On the other hand, if you want to create a simple website, it will not be costly. Second, the size of the infrastructure would vary based on the load your app needs to handle. Third, depending on the features required, developer costs will also be high or low.