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.

Here are some key features of Double Commander:

Unicode support
All operations working in background
Multi-rename tool
Tabbed interface
Custom columns
Internal text editor (F4) with syntax hightlighting
Built in file viewer (F3) to view files of in hex, binary or text format
Archives are handled like subdirectories. You can easily copy files to and from archives. Supported archive types: ZIP, TAR GZ, TGZ, LZMA and also BZ2, RPM, CPIO, DEB, RAR.
Extended search function with full text search in any files
Configurable button bar to start external programs or internal menu commands
Total Commander WCX, WDX and WLX plug-ins support
File operations logging