Formal:
* De nada: This is the most common and general way to say "you're welcome." It literally means "of nothing."
* Disponha: This means "be at your disposal" and is a more polite and formal way to say "you're welcome."
Informal:
* De nada: This is also used in informal contexts.
* Por nada: This means "for nothing" and is a less formal way to say "you're welcome."
* Imagina: This means "imagine" and is a very informal way to say "you're welcome." It's often used between friends or family.
* Não tem de quê: This means "you don't have to [thank me]" and is a more polite way to say "you're welcome" in informal contexts.
The best way to choose which phrase to use depends on the situation and your relationship with the person you're talking to.