How do you say hey What is up in french?

There are a few ways to say "Hey, what's up?" in French, depending on the context and formality:

Informal:

* Salut, ça va ? (This is the most common and versatile option)

* Coucou, ça roule ? (A bit more playful and friendly)

* Yo, quoi de neuf ? (Very informal, slangy)

* Hey, quoi de neuf ? (Similar to the above, but slightly less slangy)

Formal:

* Bonjour, comment allez-vous ? (This is a polite way to greet someone you don't know well)

* Bonjour, comment allez-vous aujourd'hui ? (A more formal version of the above)

Note:

* "Ça va ?" means "How are you?"

* "Ça roule ?" means "How's it going?"

* "Quoi de neuf ?" means "What's new?"

The best way to choose which phrase to use is to consider your relationship with the person you are talking to.