From Epic Wiki

As I couldn't find any UML documentation of the internals of the Unreal Engine, I've decided to create this new section on the wiki.

The idea is to keep a list here of all the other pages on the wiki that contain any UML diagrams representing parts of the Unreal Engine.

Because I was interested in understanding how the engine is initialized I've created a sequence diagram of that process. For reference, the tool I've used to create the model is called Visual Paradigm and I've used the Community version which is freely available. The diagram was exported as a "background-less" png image with a 150dpi resolution.

Please note that the UML diagrams listed here are not necessarily a complete, accurate representation of the actual code implementation, but rather an high view representation with the goal of making understanding the inner works of the Unreal Engine easier and quicker.

List of UML diagrams