Formal:
* "Allez-vous bien ?" (Are you well?) - This is the most formal and polite way to ask.
* "Êtes-vous en bonne santé ?" (Are you in good health?) - This is also a formal and polite way to ask, focusing on physical well-being.
Informal:
* "Ça va ?" (How are you?) - This is a very common and informal way to ask, similar to "How are you?" in English.
* "Tout va bien ?" (Is everything alright?) - This is also informal and used to inquire about someone's general well-being.
* "Tu vas bien ?" (Are you doing alright?) - This is a more casual and friendly way to ask, used among friends.
In a situation of concern:
* "Est-ce que vous allez bien ?" (Are you alright?) - This is used to express concern for someone's well-being.
* "Y a-t-il un problème ?" (Is there a problem?) - This is used to directly ask if something is wrong.
The best way to say "Are you OK" in French depends on the situation and your relationship with the person you are speaking to.