〜(よ)うか: shall I ...?; I wonder whether to ...

Offers to do something among friends, or wonders aloud whether to do it.

Volitional form + か. Casual form of 〜ましょうか: 手伝おうか？ Also used to talk to yourself when deciding: どうしようか. 〜ようかな is a gentle thought about a plan.