RoboMirror is a GUI front-end for the quite popular Robocopy.exe command-line utility for Windows. Robocopy is shipped with Windows since Vista and available as free SDK tool for previous Windows versions (RoboMirror already includes it). It allows to robustly synchronize two directory trees, both locally and across the network. It is therefore often used for mirroring purposes, e.g., as a powerful yet free backup utility.