The best open source alternative to GoodSync is Syncthing, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to GoodSync and many of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to GoodSync are FreeFileSync (Free, Open Source), Duplicati (Free, Open Source), rsync (Free, Open Source) and Rclone (Free, Open Source).
OneWaySynchronize is a Windows command line tool for backing up files from A (source) to B (destination). It will make sure that B is an exact copy of A, by copying files and overwriting and deleting files on B. The original A files are never modified in any way.
Backer is a visual front end to the rsync command. It allows the user to select multiple folders and back them up to multiple locations. It stores your backup settings for you so that all your backups can be run easily using a single button click.
FTPbox is an open-source application that allows you to synchronize your files to your own host, via FTP. This way, you can access your files anywhere, without having to pay for disk space on some 3rd-party website!.
Kup is created for helping people to keep up-to-date backups of their personal files. Connecting a USB hard drive is the primary supported way to store files, but saving files to a server over a network connection is also possible for advanced users.