I have PHP application that is completely procedural (No PHP Classes). In my case, is there any formal diagrams I can draw to show how my web application that is equivalent to a UML class diagram for OOP based applications.

Thanks all
['https://Stackoverflow.com/questions/681226', 'https://Stackoverflow.com', 'https://Stackoverflow.com/users/51649/']
You could make some Hatley-Pirbhai models:

<http://en.wikipedia.org/wiki/Hatley-Pirbhai_modeling>
It's not because the implementation (or even the design) is procedural, that the business model is.

Though you may not find explicit reference to classes in your code, they may still be there, hidden, scattered through global variables etc, functions manipulating some globals, ...

So in order to describe your app, you *may* still be able to use a (conceptual) class diagram.