(for Macintosh OS X 10.6.8 and later, up to 10.12.6. May work in 10.13, but not yet tested) Welcome to the CopyDrop home page. CopyDrop was written by Emmett Gray.
CopyDrop is distributed as shareware. The unpaid version is fully functional, but has a built-in startup delay. This delay can be avoided by buying a registration code: send $10.00 US via PayPal to egray AT handheldfilm DOT com, replacing the capitalized words with the usual symbols. CopyDrop used to have a shareware distributor, Kagi, but unfortunately they have gone out of business as of August 2016, so sending money directly to me is now the only way to get a code.
Download CopyDrop version 2.8 for OS X 10.6.8 through 10.12.6
The concept of CopyDrop is to make it possible to use the Finder to drag and drop folders, volumes, and files in order to make "smart" copies of them, meaning that identical items already in the destination are not re-copied, saving time. There are two modes, "replace" and "merge". In "replace" mode, any items existing only in the destination will be removed such that the result will be a destination identical to the source. In "merge" mode, unique items in the destination are untouched such that the destination contains all files that were previously there (and not in the source) plus every file in the source.
The Complete CopyDrop User Guide Online
For earlier operating systems, these versions are still available:
Download CopyDrop version 2.4 for OS X 10.6 through 10.8
Download CopyDrop version 2.2 (Universal Binary for all Macs, OS X 10.4.2 through 10.5.x)
For even earlier operating systems, this version is still available:
Download CopyDrop version 1.0.3 (PPC only, OS X 10.3.2 through 10.3.9 and 10.4.1)