My antivirus flagged ReplaceKeys. Is it a virus?

No, ReplaceKeys is not a virus. Some antivirus programs flag prank software because it intercepts keyboard input and runs hidden in the background -- behaviors that can resemble a keylogger. However, ReplaceKeys does not record, store, or transmit any keystrokes. It simply swaps one key for another as a joke. It has been verified safe and scanned with VirusTotal.