Whatsapp in Processing?

is it possible to make an app on phone like whatsapp?

I don’t see any reason it couldn’t be done. You’d most likely need to include some libraries from Java ecosystem. Next question is would it be sensible? I don’t think it is. Some parts of messaging and especially video or phone calls over the internet require lot’s of processing power, so they would be implemented with techniques and languages closer to hardware.

Then there’s the server side stuff. I don’t know would that be possible with processing?

sensible no. but I want to make a cool app

Yes, you can build an app. But there’s a lot more to it than the user interface.

Shameless self-promotion: here is an article I wrote that outlines the kinds of things you need to think about if you want to build a social app:

It doesn’t have to be a social app, just a very small mini game is enough