Duplicacy

Duplicacy is a new generation cloud-backup tool supporting 5 major cloud-storage providers (Amazon S3, Google Cloud Storage, Microsoft Azure, Dropbox, and Backblaze), as well as local disks and SFTP servers (such as Mac/Linux computers or NAS boxes). Duplicacy is the only cloud-backup tool that offers all the following 7 essential features:

• Incremental backup: only back up what has been changed
• Full snapshot : although each backup is incremental, it must behave like a full snapshot for easy restore and deletion
• Deduplication: identical files must be stored as one copy (file-level deduplication), and identical parts from different files must be stored as one copy (block-level deduplication)
• Encryption: encrypt not only file contents but also file paths, sizes, times, etc.
• Deletion: every backup can be deleted independently without affecting others
• Concurrent access: multiple clients can back up to the same storage at the same time
• Snapshot migration: all or selected snapshots can be migrated from one storage to another

Duplicacy also comes with an elegantly designed GUI that features one-page configuration to allow you to quickly set backup schedules and retention policies. You can also easily configure advanced options such as email notifications, automatic start on logon, and exclude/include patterns.

Best of all, Duplicacy is completely free for personal use, without any adware or any limited features. For commercial use, the subscription cost is extremely low -- only $2 per month for each computer.