What is up in french?

The most common and natural way to say "What's up?" in French is:

"Ça va ?" (pronounced "sah vah")

This literally translates to "How are you going?" but it's used as a casual greeting just like "What's up?" in English.

Here are some other options, depending on the context:

* "Quoi de neuf ?" (pronounced "kwah duh nœf") - Literally means "What's new?" and is a slightly more formal way to ask what's going on.

* "Comment ça va ?" (pronounced "koh-moh sah vah") - A slightly more formal way to ask "How are you?"

* "Coucou !" (pronounced "koo-koo") - A very informal and friendly greeting, similar to "Hey!"

* "Salut !" (pronounced "sah-loo") - A very casual greeting, similar to "Hi!" or "Hello!"

The best option will depend on who you are talking to and the context of the conversation.