PuTTYGen Generation of Public Keys

Is there a comparable program that will create public and private keys that can be used with the WinSCP (we are using WinSCP 4.1.9) for someone using a MAC computer/platform?

Also, is there a WinSCP GUI download that will work with the same computers?

I would prefer a freeware solution but will look into anything at this point!

Thank you so much!
:?: