I have been using FolderMatch for a long time in order to synchronize file between the main computer I use and the synology file server. However, perhaps because the synology is linux based, Foldermatch did not handle access and authentication correctly. It was impossible to delete files on the synology network disk. Otherwise it is a great tool. I then tried OpenSync, but soon ran into the problem that it does not support to not check on file size and date. Basically, pictures, mp3, etc. doesn’t really change and in most cases the file size difference is due to the different file systems on the local pc and the synology. So to get a speedy synchronize I want to omit that check for many folders. My latest test is Beyond Compare, a good old and reknown file comparison tool that also includes folder synchronize. So far it seems to work ok – it support both network access and one can turn off size and date check.