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Duplicati
LGPL-2.1Duplicati replaces proprietary cloud backup services like Backblaze with an open-source client that encrypts and deduplicates files before upload.
Open-source alternative to — compare it against:
Overview
Duplicati runs a local web interface that splits files into compressed, AES-256 encrypted blocks before uploading them to cloud storage or local media. By executing deduplication and cryptographic operations on the host computer, it ensures destination servers never receive unencrypted filenames, directory structures, or encryption keys. The software functions on Windows, macOS, Linux, and Docker as a self-managed backup engine for personal data.
Why Duplicati instead of Backblaze
Backblaze Computer Backup bundles cloud storage and desktop software into a closed ecosystem. While Backblaze offers a private encryption key option, web restores require submitting your passphrase to Backblaze servers so they can assemble download archives, briefly exposing data to the host. Duplicati enforces a zero-trust model: files are encrypted locally with AES-256 or GnuPG before leaving your network. No external provider holds your decryption keys, and restores execute on your local machine.
Storage destination freedom also separates the two tools. Backblaze tethers computers to its proprietary cloud, charges per workstation, and ignores Linux desktops or network-attached storage on personal plans. Duplicati decouples backup software from storage hardware, targeting Backblaze B2, Amazon S3, Google Drive, Microsoft OneDrive, or home network shares. The tradeoff is maintenance overhead: Backblaze manages backend upkeep automatically, while Duplicati requires you to manage storage credentials, configure retention rules, and maintain local database health.
What it does well
- Browser-based wizard that configures storage targets, schedules, and file filters without terminal commands.
- Broad destination support across Google Drive, Microsoft OneDrive, Dropbox, SFTP, and local network drives.
- Client-side AES-256 encryption that keeps personal documents and photos private before transfer.
- Block-level deduplication and compression that upload only modified file fragments after the initial run.
- Automated scheduler that runs unattended backups on custom hourly intervals or set weekdays.
- Windows Volume Snapshot Service (VSS) integration to back up open spreadsheets and working files without closing applications.
Limitations
- Rebuilding a corrupted local SQLite database from remote storage requires downloading and parsing all remote indexes, which can take days on large datasets (GitHub issue #4041).
