Duplicati is a backup client that securely stores encrypted, incremental, compressed backups on local storage, cloud storage services and remote file servers. The Duplicati project was inspired by Duplicity and had similar functionality until 2008. In that year the storage model was redesigned completely and the program was rebuilt from scratch. This manual describes Duplicati 2, the version based on the new storage model. Duplicati works with standard protocols like FTP, SSH, WebDAV as well as popular services like Microsoft OneDrive, Amazon Cloud Drive & S3, Google Drive, box.com, Mega, hubiC and many others. Duplicati is free software and open source. You can use Duplicati for free even for commercial purposes. Source code is licensed under LGPL. Duplicati runs under Windows, Linux, MacOS. It requires .NET 4.5 or Mono. Duplicati was designed for online backups from scratch. It is not only data efficient but also handles network issues nicely. E.g. interrupted backups can be resumed and Duplicati tests the content of backups regularly. That way broken backups on corrupt storage systems can be detected before it’s too late. Backup files and folders with strong AES-256 encryption. Save space with incremental backups and data deduplication. Run backups on any machine through the web-based interface or via command line interface. Duplicati has a built-in scheduler and auto-updater. Duplicati uses strong AES-256 encryption to protect your privacy. You can also use GPG to encrypt your backup. Duplicati is configured by a web interface that runs in any browser (even mobile) and can be accessed - if you like - from anywhere. This also allows to run Duplicati on headless machines like a NAS (network attached storage).