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

Duplicati is a backup tool, not a file sync tool.

Acronis True Image is a software product produced by Acronis that provides data protection including, backup, archive, access and recovery.

Synkron is a multiplatform Qt application designed for synchronizing two or more folders. It is written in C++ and uses the Qt4 libraries. Synkron is distribu…