Is it “would of” or “would have”?

“Would” is a modal verb that’s often used along with the auxiliary verb “have” to indicate that something was possible in the past but no longer is (e.g., “She would have been a professional athlete if she hadn’t broken her leg”). It can be contracted to “would’ve.”

People sometimes mistakenly write “would of” because of its similar pronunciation. However, “would of” is never correct.