I need an application that can sync two folders. One (original source) is on my MacBook and the other is on a Western Digital Hard Drive connected to a NAS on my network. Is there any free application that can do this? Thanks.
rsync is a commandline app thats already on your Mac. Run a terminal and do 'man rsync' to find out more. There are a few GUI frontends for rsync that are free and usable too.