Formal:
* Tudo está bem: This is the most literal and formal translation.
* Tudo em ordem: This means "everything is in order" and implies that everything is fine.
Informal:
* Tudo bem: This is the most common and casual way to say "everything is okay".
* Está tudo tranquilo: This means "everything is calm" and implies that things are peaceful and uneventful.
* De boa: This is a very informal and slang term that means "chill" or "no worries".
Other options:
* Não há problema: This means "no problem" and implies that there are no issues.
* Está tudo certo: This means "everything is right" and implies that everything is as it should be.
Example:
* "Como você está?" - "Tudo bem, obrigado." (How are you? - I'm fine, thank you.)
The best way to choose the right phrase depends on the situation and your relationship with the person you are talking to.