muCommander is a lightweight, open-source, cross-platform file manager that will run on any operating system supporting Java. Developed by Maxence Bernard
License: Open Source
FreeCommander is primarily aimed at Windows users and offers a range of features including dual-pane interface and file synchronization, but lacks cloud storage support. muCommander, on the other hand, is a cross-platform file manager that is lightweight and easy to use, but it has fewer advanced features.