zsync: zsync (client-side implementation of the rsync algorithm) zsync: zsync: zsync is a file transfer program. It allows you to download a file zsync: from a remote web server, where you have a copy of an older version of zsync: the file on your computer already. zsync downloads only the new parts zsync: of the file. It uses the same algorithm as rsync. zsync: zsync: zsync: zsync: zsync: