Meld - What is Meld? Meld is a visual diff and merge tool targeted at developers.

GoodSync - GoodSync provides highly reliable file backup and synchronization for both individuals and businesses.

WinMerge - WinMerge is an open source differencing and merging tool for Windows.

rsync - rsync is a file transfer program for Unix systems. rsync uses the "rsync algorithm" which provides a very fast method for bringing remote files into sync.

Beyond Compare - Beyond Compare allows you to compare files and folders.

FreeFileSync - FreeFileSync is a free open source data backup software that helps you synchronize files and folders on Windows, Linux and macOS.