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.
Files is a file manager which leverages the latest features of the Windows platform including Fluent Design, seamless updates, and APIs which enable the performance and lifecycle behavior that users expect.
File Explorer (Windows 10), previously known as Windows Explorer, is a file manager application that is included with releases of the Microsoft Windows operating system from Windows 95 onwards. It is sometimes referred to as the Windows shell, explorer.
GNOME Files, formerly known as Nautilus, is the official file manager for the GNOME desktop, giving the user a simple way to navigate and manage its files.
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.
Index is a convergent file manager, it the user with a simple way to navigate and manage files. Index incorporates features such as miller columns, embedded terminal, split views, file previews, experimental WebDAV support, tags.
Caja is a fork of Nautilus from GNOME 2 and is native to the MATE Desktop Environment. It is a file manager like the Windows Explorer (not to confuse with Internet Explorer/Microsoft Edge), but for Unix/BSD and Linux.
TotalFinder works like the normal Finder but adds tabs, dual panel, colored labels and other features. My goal is to improve Finder in a few areas where it is lacking but keep the general design.
Saladin is an open source dual-pane file manager for Windows which merges the capabilities of Windows Explorer with the well known and easy to use orthodox user interface.
Last version is from May 2017. See here: https://saladin.mimec.org/news