Krusader!

Double Commander is a cross platform open source file manager with two panels side by side. It is inspired by Total Commander and features some new ideas.

FreeCommander is an easy-to-use alternative to the standard windows file manager. The program helps you with daily work in Windows. Here you can find all the necessary functions to manage your data stock. You can take FreeCommander anywhere – just copy the installation directory on a CD or USB-Stick – and you can evenwork with this program on a foreign computer.

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 and run commands in the subshell. Internal viewer and editor are included.

XYplorer is a file manager for Windows. It features tabbed browsing, a powerful file search, a versatile preview, a highly customizable interface, optional dual pane, scripting engine, and a large array of unique ways to efficiently automate frequently recurring tasks. It’s fast, light, and portable.

QTTabBar is an extension for Windows Explorer that brings tabbed browsing to Microsoft's file browser. It comes with a number of nifty features including a favorites function for launching folders and applications, groupings of folders that can be opened together, tooltip preview functions for a number of file types, and others. It is also highly customizable and hotkey-enabled.

Q-Dir makes your files and folder easy to manage. Fast and easy access, with an amazing Quadro-View (4 panes) technique. You dont have to renounce the usual, Drag and Drop, all Views, and other functions of your system. No! Q-Dir gives you other nice functions, that make you happy. One can save many hand moves and also time!

Dolphin is a file manager for KDE focusing on usability. Has three view modes: Icon, Detail and it used to have Column View like in Finder (it is not available in current version due to problems with maintaibility). Supports FTP, SCP and other protocols. Highly configurable.

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 is fast and responsive with a good start up time and directory load time. Thunar is accessible using Assistive Technologies and is fully standards compliant.

Multi Commander has a lot of file manager features. This list It is not even close to complete. There are so many features and tweaks in Multi Commander that not everything can be listed here.

Far Manager is a program for managing files and archives in Windows operating systems. Far Manager works in text mode and provides a simple and intuitive interface for performing most of the necessary actions:

Explorer++ is a free file manager for Windows. Available on Windows XP and above, it features the same familiar interface as Windows Explorer, while introducing several enhancements and improvements for a much richer file browsing experience.

"Dual pane file manager and SFTP/FTP client for Mac OS XForkLift 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 interface. Dual-pane view will dramatically increase your productivity along with state-of-the-art features like live preview, spring loaded folders and any-to-any workflow. All this to be topped by tabs, to keep your workspace nice and clean." »

An extremely fast and lightweight file manager which features tabbed browsing and user-friendly interface.

Commander One is dual-pane file manager for OS X created in Swift, which enables you to manage your files in the best possible way.