was hamlet insane?

No, Hamlet wasn't insane.

'Melancholy', I said, not dejection, nor yet insanity. That Hamlet was not far from insanity is very probable. His adoption of the pretence of madness may well have been due in part to fear."

Add this source;

http://shakespeare-navigators.com/bradley/tr153.html

Again, I'd have to disagree. His "insanity" or "craft" has been up for debate since the plays inception. Their are some pretty convincing arguements on both sides.