A new generation cross-platform cloud backup tool

Duplicacy backs up your files to many cloud storages with client-side encryption and the highest level of deduplication




Feature-Driven Design

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
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)
Encrypt not only file contents but also file paths, sizes, times, etc.
Every backup can be deleted independently without affecting others
Concurrent backup
Multiple clients can back up to the same storage at the same time
Backup migration
All or selected backups can be migrated from one storage to another
Seven essential features

Fossil Collection

Lock-Free Deduplication

Duplicacy is the only backup tool to support all 7 essential features listed above, because it is built on top of a new idea called Lock-Free Deduplication, which works by relying on the basic file system API to manage deduplicated chunks without using any locks. A two-step fossil collection algorithm is devised to solve the fundamental problem of deleting unreferenced chunks under the lock-free condition, making deletion of old backups possible.


Thanks to Lock-Free Deduplication, Duplicacy is readily amenable to most cloud storage services without compromising any essential features required of a state-of-the-art backup tool. In addition, Duplicacy also supports local disks and your own SFTP servers such as Mac or Linux computers, or NAS boxes.

Cloud Storages

Duplicacy GUI Screenshot

Ease-of-use GUI

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

Powerful Command Line Interface

The GUI version is a user-friendly frontend to the Duplicacy backup engine which can also be invoked from the command line. To fully exploit the power of Duplicacy, you can run the command line executable either manually, or from a script for more flexibility. Many features such as adding additional storages, copying backups from one storage to another, changing encryption passwords, are only available in the command line version.

Duplicacy Command Line

Duplicacy Source Code

Source Code Availability

The source code of the command line version of Duplicacy is released on our github page. With source code access, you will have a better understanding of how Duplicacy works internally, and be confident that your backups will always be kept safe and never fail. You can also make customizations or even add new features on your own to fit your needs.

The command line version is free for individual users, and commercial licenses can be purchased at a low cost of $20 per user per year.


If you are an IT service provider offering managed backup service to your customers, we can build a customized GUI version of Duplicacy that has only your logo and brand name, at no extra charge. It can also be modified to have a pre-configured storage with credentials automatically populated.

If you are interested in this option, please contact us for more details.

Duplicacy Customization