Duplicati is a backup program for Windows, macOS, and Linux from Duplicati Inc. Its free core compresses and encrypts backup data, keeps file versions, and restores them to local or remote locations. A browser interface controls jobs through a local server; the desktop tray icon opens that interface and shows status.
Sources inside a backup job
You give each job a name, choose files or folders, and set its destination, encryption, schedule, and retention rules. A folder selection includes its descendants. Duplicati can narrow that selection through exact paths, wildcards, regular expressions, or predefined groups for caches and temporary files.
The first full filter match decides what to include. Excluding a folder also removes its children from the scan. A proprietary disk module accepts complete disks with their partition tables or individual partitions. Reading those sources requires administrative access.
Online account data
The Microsoft 365 module takes tenant and application credentials, then reads mail, files, and other content through Microsoft Graph. Google Workspace uses administrator and service-account credentials to read the data types you choose. These modules preserve mail and structured objects in formats such as MIME, EML, and JSON.
Production tenant backups require module licenses. Restore can write data locally or recreate items through the provider’s API. Google Groups and Sites support backup only.
Where the volumes go
Duplicati connects a job to a storage backend. Local paths, network shares, S3-compatible storage, SFTP, WebDAV, and cloud-drive services provide different destinations. You supply the provider’s connection details and credentials, then the connection test checks them.
Each backup needs its own destination folder. The file backend can use a local drive, removable media, or a network location that the filesystem can reach.
Reusing data blocks
The backup engine reads files in blocks and checks whether each block already exists in the backup. It adds new blocks to volumes, compresses and encrypts them, and uploads the results. A file list records how to reconstruct the complete files, including the blocks that earlier runs already contain.
Duplicati’s AES encryption uses a separate random key for each volume and adds an integrity signature. You choose a passphrase; the program also offers generation and strength checks. Losing that passphrase prevents recovery of the data. After a backup, the engine checks the destination and downloads sample volumes for verification.
Schedules and version retention
A schedule starts the job automatically, while Start runs it immediately from the interface. Later runs process new and changed data.
Retention can remove versions by age, keep a particular count, or use time buckets with different spacing. Smart retention keeps fewer versions farther back. Duplicati applies deletion rules after a backup and retains at least one version. Compacting rewrites remote volumes to discard data that no remaining version references.
Choosing what to restore
The restore view lets you choose a backup version and then browse its files and folders. You can write them to their original paths or another location. Timestamp suffixes let several versions coexist in the target folder.
Duplicati normally uses a local database as an inventory of the remote backup. If that database or the original configuration disappears, destination credentials and the encryption passphrase allow recovery from the backup data. The program reconstructs the inventory it needs.
Disk restores can write a whole disk or an individual partition. Users unmount the target before restoring, and the operation needs administrative access.
A separate sync job
Sync mode copies source files directly to a destination in one direction. It does not apply the normal backup’s deduplication, compression, encryption, or version history. You choose this mode when creating the job; an existing job cannot switch between backup and sync.
Sync can compare against a destination listing, consult a local record of remote files, or upload everything. An optional deletion setting removes destination files during synchronization, while destination folders remain.
Reports and scripts
Duplicati displays warnings and errors through desktop notifications and can send operation reports by email, HTTP, Telegram, or XMPP. A live-reporting module sends progress to a URL you supply.
Before and after scripts connect a job to other tasks. A required preparation script can stop the operation if it fails. Completion scripts receive results as text or JSON, so their logic can respond to the outcome. The command-line tools also run backup operations without the browser interface.
Connecting machines to the Console
The optional Duplicati Console collects machine status and backup results in account dashboards. An existing desktop installation connects through its remote-management settings. The free plan covers basic monitoring.
Pro adds missed-backup alerts and remote management. Enterprise adds organizations, access controls, and backup configurations that administrators apply across machines. Its separate Agent deployment form supports environments without local interface access.
