FreeFileSync

FreeFileSync compares the contents of a source folder with a target folder and synchronizes them, copying only the files that have changed. It creates and maintains backup copies of important data, minimizing transferred data by detecting differences rather than copying everything each time. The software runs on Windows, macOS, and Linux and is distributed as open‑source code.

The tool is aimed at users who need reliable folder synchronization and backup, such as individuals managing personal files, developers handling project directories, or small teams maintaining shared resources. It supports high‑DPI displays, multi‑folder pairs, and provides logging and error handling to aid troubleshooting.

Distinctive aspects include its cross‑platform availability, open‑source licensing, and a focus on transferring only the minimal required data during synchronization. The project is sustained through ad revenue and donations, and a Business Edition offers licensing options for resellers and device‑license management.