Sync HDD

I have a iMac i7 OS X Mavericks and a Mac mini OS X 10.8.5 both connected to a local Wi-Fi network and share files [work in progress].

What I would like to do is schedule a sync of a nominated folder on one Desktop with the other Desktop so that the contents of the folders on each desktop at a nominated time are identical.

Then at another time I would like to schedule the same process but write the files in the source folder to Dropbox so that the contents of those folders at a nominated time are identical.

I do not want the files worked on during the day being synced each time they are saved rather as a scheduled end of day process.

It would appear to me that this process might require a third party application as I have been unable to identify anything within the Apple Software offering that performs this type of task.

Can anyone without obligation refer me to a developer who has a program that will perform my requirement?

Prompt replies are always appreciated. Ant..