I am looking for a solution to sync folder pairs between a NAS and multiple local macs. Each of the macs could edit files and the other macs should then get synced automatically. Basically my own local version of Dropbox without using "cloud-storage".

I have looked into solutions using rsync. As I understand it rsync is not really capable of doing a bi-directional sync. I also do not want to necessarily invoke the sync process. I would prefer a daemon running in the background - waiting and checking for changes and then syncing them "live".

The program should also be flexible enough to recognize that it sometimes (in the case with laptops) can not reach the NAS. It should then just wait for the connection to be back again, without bugging me ever few minutes.

I have looked into synk, folderwatch, rsync and a few others, but I haven't really found a solution.

Isn't there something like "offline folders" from microsoft for the mac?

Thanks

PS: just for clarification - I don't want to sync for backup purposes, instead I am wanting to sync so that all macs have a local copy of the most recent changes to files.