FreeFileSync is an free open source file synchronizing program written in C++ for Linux, Macintosh, and Windows which uses a very unobtrusive nagware model. It supports multi-directional synchronization, several methods of comparison, remote destinations, real-time checking, and a scheduler.
I found this program after searching for a replacement for the default backup software of my Synology NAS which was far too slow. After using it for awhile and realizing how amazing it is, I also stopped using SyncToy, which was a similar program.
- The program is not only free and open source, but it doesn't even include ads or adware. Instead, you can make a donation to unlock additional features.
- Since you can specify how you want to compare files (time, size, or content), you can choose between quick and thorough backups. You can also specify what to do with old files (delete, recycle, or version), and whitelist/blacklist files.
- The real-time scanner and scheduler make the program very hands-free.
- You can synchronize between remote servers through FTP, FTPS, and SFTP, and even USB devices that use MTP.
- The synchronization gives a nice line graph showing its process.
- The program receives frequent updates and bug fixes.
- By default, the comparison halts when it encounters an error rather than queuing the file and moving on.