There currently is no v3 endpoint for creating applications. The UI uses private APIs to create and manage apps. There is no official documentation for these private APIs, and they don’t have any support guarantees, meaning they can change or be removed without notice. Using the private APIs is at your own risk. Do you mind if I ask what your use case is? Do you have a lot of apps to create and automation would make it easier for you, or do you have a workflow where you need to programmatically create apps?