* "All well" is correct when used as an adjective phrase, meaning "everything is fine." For example:
* "Is everything all well?"
* "I hope all is well with you."
* "Are well" is correct when used as a verb phrase, meaning "are in good health." For example:
* "How are you? Are you well?"
* "They are well and living happily."
In short:
* "All well" describes a state of being.
* "Are well" describes a condition of health.