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Duplicati is a free, open-source backup software used by privacy-conscious individuals, home users, and technical specialists around the world on Windows, macOS, and Linux. It provides AES-256 client-side encryption, incremental backup with deduplication, cloud backup to Google Drive, OneDrive, Dropbox, Amazon S3, and many other providers, local and network backup, flexible scheduling, and data compression, all managed through a browser-based interface. This review takes a neutral and practical look at what the software does well, where it performs consistently, and who is most likely to find it useful.

The defining characteristic of Duplicati is its approach to cloud backup privacy. All encryption and compression happen on the local machine before any data is uploaded, which means the cloud storage provider never receives unencrypted files. Only the user holds the encryption keys. For users who want to use public cloud storage for backup but are not comfortable with the idea of the storage provider having access to their files, this client-side encryption model provides a meaningful privacy advantage over services that encrypt data only after it reaches their servers.

Duplicati is entirely free and open source, with no entry caps, no subscription tiers, and no feature restrictions. The full feature set including cloud integration, encryption, scheduling, and deduplication is available at no cost. For users who want a capable encrypted cloud backup solution without paying for a commercial service, Duplicati is one of the most complete options available.

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What Is Duplicati

Duplicati is a free, open-source backup utility that encrypts and compresses data locally before uploading it to a wide range of cloud storage providers or local destinations. It runs on Windows, macOS, and Linux, and is managed through a web-based interface accessible from any browser on the local machine. The source code is publicly available, and the software has an active community of contributors and users.

The software supports over twenty storage backends including Google Drive, OneDrive, Dropbox, Amazon S3, Backblaze B2, Azure Blob Storage, FTP, SFTP, and WebDAV. Backups are encrypted using AES-256 before leaving the local machine, ensuring that storage providers receive only encrypted data. Incremental backups after the initial run upload only the changed blocks of data rather than entire files, reducing both upload time and storage consumption over time.

Duplicati is positioned as a technically capable, privacy-focused backup tool for users who are comfortable configuring software through a browser interface and want full control over their backup destinations and encryption keys without paying for a commercial solution.

Key Features

Client-Side AES-256 Encryption: All data is encrypted on the local machine before being uploaded to any destination. The encryption key is set by the user and is never transmitted to Duplicati or the storage provider, ensuring that only the user can decrypt the backup.

Broad Cloud Provider Support: Duplicati connects to over twenty storage backends including Google Drive, OneDrive, Dropbox, Amazon S3, Backblaze B2, Azure Blob Storage, FTP, SFTP, and WebDAV. This gives users the flexibility to back up to whichever service best fits their existing setup or cost preferences.

Incremental Backup with Deduplication: After an initial full backup, subsequent jobs upload only the data blocks that have changed since the last run. Deduplication further reduces storage usage by avoiding duplicate data across backup versions, keeping long-term storage consumption manageable.

Data Compression: Files are compressed before encryption and upload, reducing the total storage space required and shortening upload duration for large backup sets.

Cross-Platform Support: Duplicati runs natively on Windows, macOS, and Linux, making it one of the few free backup tools that covers all three major desktop operating systems with the same feature set.

Web-Based Interface: The software is configured and managed through a browser-based dashboard rather than a traditional desktop application. This makes it accessible from any browser on the local machine and allows the backup service to run as a background process without requiring a visible application window.

Flexible Scheduling: Backup jobs can be configured to run on custom schedules with precise timing controls, supporting anything from frequent incremental runs to weekly full backups depending on the user’s storage and bandwidth constraints.

Local and Network Backup: In addition to cloud targets, Duplicati supports backup to local hard drives, external drives, NAS devices, and network shares, allowing users to maintain both local and offsite copies within the same tool.

Performance Review

Encryption and Pre-Upload Security

In tested scenarios, Duplicati encrypted backup data locally before uploading, and the resulting files stored on the cloud destination were unreadable without the correct passphrase. Restoration required the same passphrase used during backup, confirming that the storage provider held no ability to access the file contents. This behavior was consistent across Google Drive and Amazon S3 targets in tested configurations.

Incremental Backup Efficiency

In tested scenarios, incremental backup jobs after the initial full backup uploaded significantly less data than the total backup set, reflecting only the files and blocks that had changed since the previous run. On datasets with moderate daily change rates, subsequent backup jobs completed in a fraction of the time required for the initial full backup. Deduplication reduced redundant data across backup versions, keeping total cloud storage consumption lower than storing independent snapshots for each run.

Web Interface and Job Configuration

In tested scenarios, the browser-based interface was accessible and functional for configuring backup jobs, selecting cloud destinations, setting encryption passphrases, and scheduling runs. The setup process for a standard cloud backup job required familiarity with cloud storage credentials such as OAuth tokens or API keys, which added initial complexity for users setting up a cloud provider for the first time. Once configured, jobs ran automatically without requiring further interaction.

Cross-Platform Consistency

In tested scenarios, Duplicati performed consistently across Windows and Linux installations using the same job configuration exported between systems. The web interface behaved identically on both platforms, and backup files created on one system were restorable on the other, confirming cross-platform compatibility of the backup format.

Pricing & Plans

Free — Complete Feature Access: Duplicati is entirely free with no feature limitations, no storage caps imposed by the software, and no subscription required. The full feature set including all cloud integrations, AES-256 encryption, incremental backup, deduplication, and scheduling is available at no cost.

The cost of using Duplicati for cloud backup depends on the storage service the user chooses to back up to, rather than on Duplicati itself. Many supported providers offer free storage tiers, and paid tiers for services like Backblaze B2 and Amazon S3 are generally low-cost for typical personal backup volumes.

Use Cases

Encrypted Cloud Backup on a Budget: The combination of client-side AES-256 encryption and support for low-cost cloud storage providers makes Duplicati a practical option for users who want encrypted offsite backup without paying for a commercial backup service.

Privacy-First Cloud Storage Use: For users who want to use public cloud storage but are not comfortable with the provider having access to their files, Duplicati’s pre-upload encryption ensures that the storage provider receives only encrypted data that it cannot read.

Cross-Platform File Protection: Native support for Windows, macOS, and Linux allows users to protect machines across all three operating systems using the same tool and backup format.

Long-Term Archive Management: Incremental backup with deduplication and compression keeps storage consumption manageable over time, making Duplicati practical for maintaining backup history across months or years without runaway storage costs.

NAS and Home Server Backup: Running Duplicati as a background service on a NAS device or home server allows automated encrypted backup of local network storage to cloud providers on a regular schedule.

Technical Users Seeking Full Control: The open-source codebase, broad provider support, and configurable encryption give technically capable users complete visibility and control over every aspect of their backup setup.

Pros and Cons

Pros:

  • Completely free and open source with no feature limitations, storage caps, or subscription fees of any kind.
  • Client-side AES-256 encryption ensures that cloud storage providers never receive unencrypted data, giving users genuine privacy over their backed-up files.
  • Support for over twenty storage backends provides flexibility to back up to whichever provider best fits the user’s cost or privacy preferences.
  • Incremental backup with deduplication and compression keeps long-term storage consumption and upload times manageable on large datasets.
  • Cross-platform support for Windows, macOS, and Linux covers mixed-OS environments within a single tool.

Cons:

  • Initial configuration, particularly setting up cloud provider credentials and understanding backup chain management, requires more technical knowledge than consumer-oriented backup tools with guided setup wizards.
  • Duplicati is designed for file and folder backup rather than bare-metal system image recovery. Users who need to restore an entire operating system from scratch will need a separate tool for that scenario.

Who Should Consider This Software

Duplicati is a strong option for privacy-focused users, technical home users, and anyone who wants free encrypted cloud backup with full control over their encryption keys and storage destinations. It is particularly well suited to users who already have a cloud storage account and want to use it for encrypted backup without paying for a separate commercial backup service, as well as Linux users who need a capable free backup tool that runs natively on their platform.

Users who want a simple, guided setup with minimal technical involvement, or who need bare-metal system image backup, will find Duplicati more complex or limited than their needs require. For users who value privacy, open-source transparency, and cost-free flexibility, Duplicati is one of the most capable free backup tools available.

Final Verdict

Duplicati delivers a technically capable and privacy-focused backup experience that is difficult to match at its price point of free. Client-side encryption, broad cloud provider support, incremental backup with deduplication, and cross-platform compatibility make it a well-rounded solution for users who want encrypted offsite backup without a commercial subscription. The browser-based interface keeps the software accessible across platforms, and the open-source codebase provides transparency for users who want to verify how their data is handled.

The main barrier is setup complexity. Duplicati rewards users who invest time in configuration, but is less forgiving for those who want a simple plug-and-play experience. For technically capable users who want free, private, and flexible cloud backup, Duplicati is an excellent choice.

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