やっぱり。

Yappari.

I knew it. / After all.

Word for word

“As I thought.”

Politeness: Casual

Plain form. Fine with family, close friends and people younger than you. Rude to a stranger or a boss.

When you would say it

When something turns out as you expected.

Worth knowing

Formal: やはり. Used with a mild sigh or smile.