GNU Midnight Commander is a visual file manager, licensed under GNU General Public License and therefore qualifies as Free Software. Its a feature rich full-screen text mode application that allows you to copy, move and delete files and whole directory trees, search for files...
Thunar is a new modern file manager for the Xfce Desktop Environment. Thunar has been designed from the ground up to be fast and easy-to-use. Its user interface is clean and intuitive, and does not include any confusing or useless options.
Thunar vs GNOME Files opinions
ForkLift is designed to be the fastest, most powerful file manager for the Mac. Connect to FTP or SFTP servers, manage your Amazon S3 account or your mobile devices over Bluetooth. All these features are beautifully integrated into a sophisticated, yet easy to use Cocoa based...
The Finder is the first thing that you see when your Mac finishes starting up. It opens automatically and stays open as you use other apps. It includes the Finder menu bar at the top of the screen and the desktop below that.
JumpFm is a minimalistic dual panel file manager (currently released only for Windows, Mac, and Linux) that lets you navigate your file system very efficiently.Discontinued
The last release was in 2017, but you can still download it and use it.
Organize files across many devices in one place. From cloud services to offline hard drives, Spacedrive combines the storage capacity and processing power of your devices into one personal distributed cloud, that is both secure and intuitive to use.
HiFile is the next evolution of file managers. Its mission is to boost your productivity every time you are working with your files or folders. It aims to be better in every aspect - more practical, more versatile, more efficient, more elegant, more customizable, more fun.
Magican File is a professional program for Mac OS X that let you search and manage files on your disks.
The company seems to be abandoned: no news since 2013. Last version, 1.1.0, released in June 2011, can be still downloaded from Apple Appstore.