Formal:
* Unafanya nini? (oo-nah-fa-nya nee-nee?) - This is the most common and direct translation.
* Unakwenda wapi? (oo-nah-kwen-da wa-pee?) - This translates to "Where are you going?" and can be used in a similar way to "What are you doing?" in English, especially when someone seems busy or is leaving.
Informal:
* Unafanya nini sasa? (oo-nah-fa-nya nee-nee sa-sa?) - This literally translates to "What are you doing now?" and is more casual.
* Unashughulika na nini? (oo-nah-shoo-goo-li-ka na nee-nee?) - This translates to "What are you busy with?" and is a more informal way to ask about someone's activities.
Other options:
* Mbona uko hivyo? (mbo-na oo-ko i-vyo?) - This translates to "Why are you like that?" and can be used to ask about someone's mood or what's going on with them.
* Unajisikiaje? (oo-na-ji-see-kia-je?) - This means "How are you feeling?" and can be used to inquire about someone's well-being.
The best way to translate "What are you doing?" in Swahili depends on the situation and your relationship with the person you're speaking to.