How to say i think you're cute in japanese?

"I think you're cute" could be "かわいいね" (kawaii ne) informally and a bit vaguely (there's no "you").
Or "かわいいですね" (kawaii desu ne) a bit more formal but still vague (again, there's no "you")
Or "あなたはかわいいね" (anata wa kawaii ne) informal with "you" (anata)
Or "あなたはかわいいですね" (anata wa kawaii desu ne) a bit more formal with "you" (anata)

You can also use "君" (kimi) instead of "あなた" (anata). I feel like "君" (kimi) would be used if a boyfriend was telling his girlfriend she's cute, but that might be just me XD

Hope this helped!! xx

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