Duplicati is a free and open-source backup tool that helps you protect your files from data loss. It works by creating encrypted, compressed, and incremental backups of your files, which you can store on your own computer, an external hard drive, or a remote server. Duplicati is designed to be cross-platform, so it works on Windows, macOS, and Linux. The web-based user interface makes it easy to set up and manage your backups, and you can even schedule them to run automatically. By only backing up the changes you've made since the last save, it saves storage space and reduces the amount of time and bandwidth needed for each backup.