What Is Duplicacy?
Prerequisites
Docker Compose Configuration
Initial Setup
Configuration
Supported Storage Backends
Cross-Computer Deduplication
Retention Policies
Advanced Configuration (Optional)
Encryption
Filters (Include/Exclude)
CLI Usage
Reverse Proxy
Backup
Troubleshooting
Web UI not accessible
Slow initial backup
Cache growing too large
Verdict
Frequently Asked Questions
Is Duplicacy free?
What is cross-computer deduplication?
How does Duplicacy compare to Restic?
Can I encrypt my backups?
What cloud storage backends does Duplicacy support?
How do I restore files from a Duplicacy backup?
Related Duplicacy is a backup tool that combines lock-free deduplication with broad cloud storage support. Its defining feature is cross-computer deduplication — multiple machines backing up to the same storage can share dedup data, dramatically reducing total storage needs. Duplicacy comes in two editions: a free CLI and a paid web UI ($20 one-time for personal use). Duplicacy's web UI edition has a Docker image maintained by the community. Create a docker-compose.yml file: Important: Replace /path/to/backup-source with the directory you want to back up, and /path/to/local-storage with your local backup destination. For cloud-only backup, you can remove the /storage volume. Duplicacy's unique feature: multiple machines can share a single storage backend and deduplicate data across all of them. This is particularly valuable for teams or households where multiple computers contain similar files. To enable: point all machines at the same storage backend with the same repository ID prefix. Duplicacy handles dedup automatically. Configure in the web UI under each backup's schedule: This keeps: all snapshots from the last day, daily for 7 days, weekly for 30 days, monthly for a year, then deletes older. Enable encryption when initializing a repository: Duplicacy uses AES-256-GCM encryption. The encryption key is derived from your password — do not lose it, as there is no recovery mechanism. Create a .duplicacy/filters file in your repository root: For users who prefer the free CLI edition: To access Duplicacy's web UI behind SSL, proxy to port 3875. For setup details, see our Reverse Proxy Setup guide. Back up the Duplicacy configuration itself: For a comprehensive backup strategy, see our Backup Strategy guide. Symptom: Cannot connect to port 3875.
Fix: Check container logs: docker compose logs duplicacy. Ensure the port mapping is correct and no other service is using 3875. Symptom: First backup takes much longer than expected.Fix: This is normal — the initial backup uploads all data. Subsequent incremental backups are fast. For large datasets, consider running the first backup to a local destination and then migrating the repository. Symptom: "Permission denied" when backing up mounted directories.Fix: Ensure USR_ID and GRP_ID environment variables match the owner of the source files. Check with ls -la /path/to/backup-source. Symptom: The cache volume consumes significant disk space.
Fix: Duplicacy caches chunk metadata locally for faster dedup. For very large repositories, the cache can grow to several GB. You can safely delete the cache contents — Duplicacy rebuilds it automatically (first backup after clearing will be slower). Duplicacy fills a specific niche: cross-computer deduplication with cloud storage support. If you back up multiple machines to the same storage, Duplicacy's shared dedup can save 30-50% more space than per-machine tools. The paid web UI ($20 one-time) provides the most polished management experience in the self-hosted backup space. However, for single-machine backup, Restic (free, larger community) or Kopia (free, built-in UI) are better choices. The CLI edition is free for personal and commercial use. The web UI edition costs $20 (one-time) for personal use or $50 for commercial use. Both editions support the same backup engine and storage backends. The web UI adds scheduling, status monitoring, and a browser-based management interface. Duplicacy's unique feature: when multiple computers back up to the same storage repository, they share deduplicated chunks. If your desktop and laptop both contain the same 5 GB folder, that data is stored only once in the backup destination. This can reduce total storage needs by 30-50% compared to per-machine deduplication tools like Restic or BorgBackup. Both use chunk-based deduplication and support multiple cloud storage backends. Duplicacy's unique advantage is cross-computer deduplication — multiple machines sharing one storage backend deduplicate across all of them. Restic has a larger community, more documentation, and is fully free. For single-machine backup, Restic is the better default choice. For multi-machine environments, Duplicacy's shared dedup can significantly reduce storage costs. Yes. Enable encryption when initializing a repository with the -e flag. Duplicacy uses AES-256-GCM encryption. The encryption key is derived from your password — if you lose the password, the backup is unrecoverable. Always store the encryption password in a secure location separate from the backup. Duplicacy supports Amazon S3, Backblaze B2, Wasabi, Google Cloud Storage, Azure Blob Storage, SFTP, and any S3-compatible service (including self-hosted MinIO). Local disk backup is also supported. Backblaze B2 ($6/TB/month) and Wasabi ($7/TB/month) offer the best cost for cloud-based backup storage. Use the web UI's restore function or the CLI: duplicacy restore -r REVISION_NUMBER. You can restore specific files or the entire snapshot. List available snapshots with duplicacy list. Each snapshot captures the complete state of your repository at that point in time. Templates let you quickly answer FAQs or store snippets for re-use. Hide child comments as well For further actions, you may consider blocking this person and/or reporting abuse
$ services: duplicacy: image: saspus/duplicacy-web:v1.8.3 container_name: duplicacy -weight: 500;">restart: unless-stopped hostname: duplicacy-server ports: - "3875:3875" # Web UI volumes: - duplicacy-config:/config # Duplicacy configuration and logs - duplicacy-cache:/cache # Dedup cache (speeds up backups) - /path/to/backup-source:/data:ro # CHANGE: directories to back up - /path/to/local-storage:/storage # CHANGE: local backup destination (optional) environment: TZ: UTC USR_ID: 1000 # Host user ID for file permissions GRP_ID: 1000 # Host group ID for file permissions networks: - backup networks: backup: driver: bridge volumes: duplicacy-config: duplicacy-cache:
services: duplicacy: image: saspus/duplicacy-web:v1.8.3 container_name: duplicacy -weight: 500;">restart: unless-stopped hostname: duplicacy-server ports: - "3875:3875" # Web UI volumes: - duplicacy-config:/config # Duplicacy configuration and logs - duplicacy-cache:/cache # Dedup cache (speeds up backups) - /path/to/backup-source:/data:ro # CHANGE: directories to back up - /path/to/local-storage:/storage # CHANGE: local backup destination (optional) environment: TZ: UTC USR_ID: 1000 # Host user ID for file permissions GRP_ID: 1000 # Host group ID for file permissions networks: - backup networks: backup: driver: bridge volumes: duplicacy-config: duplicacy-cache:
services: duplicacy: image: saspus/duplicacy-web:v1.8.3 container_name: duplicacy -weight: 500;">restart: unless-stopped hostname: duplicacy-server ports: - "3875:3875" # Web UI volumes: - duplicacy-config:/config # Duplicacy configuration and logs - duplicacy-cache:/cache # Dedup cache (speeds up backups) - /path/to/backup-source:/data:ro # CHANGE: directories to back up - /path/to/local-storage:/storage # CHANGE: local backup destination (optional) environment: TZ: UTC USR_ID: 1000 # Host user ID for file permissions GRP_ID: 1000 # Host group ID for file permissions networks: - backup networks: backup: driver: bridge volumes: duplicacy-config: duplicacy-cache:
-weight: 500;">docker compose up -d
-weight: 500;">docker compose up -d
-weight: 500;">docker compose up -d
duplicacy prune -keep 0:365 -keep 30:30 -keep 7:7 -keep 1:1
duplicacy prune -keep 0:365 -keep 30:30 -keep 7:7 -keep 1:1
duplicacy prune -keep 0:365 -keep 30:30 -keep 7:7 -keep 1:1
duplicacy init -e my-repo-id sftp://user@host/backup
duplicacy init -e my-repo-id sftp://user@host/backup
duplicacy init -e my-repo-id sftp://user@host/backup
# Exclude patterns
-node_modules/
-.-weight: 500;">git/
-*.tmp
-__pycache__/
-.cache/ # Include patterns
+Documents/
+Photos/
# Exclude patterns
-node_modules/
-.-weight: 500;">git/
-*.tmp
-__pycache__/
-.cache/ # Include patterns
+Documents/
+Photos/
# Exclude patterns
-node_modules/
-.-weight: 500;">git/
-*.tmp
-__pycache__/
-.cache/ # Include patterns
+Documents/
+Photos/
# Initialize a repository
cd /path/to/backup-source
duplicacy init my-repo sftp://user@host/backup # Run a backup
duplicacy backup # List snapshots
duplicacy list # Restore from snapshot
duplicacy restore -r 42 # Restore revision 42 # Prune old snapshots
duplicacy prune -keep 0:180 -keep 7:30 -keep 1:7
# Initialize a repository
cd /path/to/backup-source
duplicacy init my-repo sftp://user@host/backup # Run a backup
duplicacy backup # List snapshots
duplicacy list # Restore from snapshot
duplicacy restore -r 42 # Restore revision 42 # Prune old snapshots
duplicacy prune -keep 0:180 -keep 7:30 -keep 1:7
# Initialize a repository
cd /path/to/backup-source
duplicacy init my-repo sftp://user@host/backup # Run a backup
duplicacy backup # List snapshots
duplicacy list # Restore from snapshot
duplicacy restore -r 42 # Restore revision 42 # Prune old snapshots
duplicacy prune -keep 0:180 -keep 7:30 -keep 1:7
# The config volume contains all settings and credentials
-weight: 500;">docker compose exec duplicacy tar czf /tmp/config-backup.tar.gz /config
-weight: 500;">docker compose cp duplicacy:/tmp/config-backup.tar.gz ./
# The config volume contains all settings and credentials
-weight: 500;">docker compose exec duplicacy tar czf /tmp/config-backup.tar.gz /config
-weight: 500;">docker compose cp duplicacy:/tmp/config-backup.tar.gz ./
# The config volume contains all settings and credentials
-weight: 500;">docker compose exec duplicacy tar czf /tmp/config-backup.tar.gz /config
-weight: 500;">docker compose cp duplicacy:/tmp/config-backup.tar.gz ./ - A Linux server (Ubuntu 22.04+ recommended)
- Docker and Docker Compose installed (guide)
- 512 MB of free RAM (minimum)
- A backup destination (local disk, NAS, S3, B2, Wasabi, etc.) - Open http://your-server-ip:3875 in your browser
- Create an admin password on first access
- Add a new backup: Repository: Path to your data inside the container (e.g., /data) Storage: Choose your backup destination: Local disk: /storage S3: s3://region@bucket-name Backblaze B2: b2://bucket-name SFTP: sftp://user@host/path Wasabi: wasabi://region@bucket-name Schedule: Set backup frequency (hourly, daily, etc.)
- Repository: Path to your data inside the container (e.g., /data)
- Storage: Choose your backup destination: Local disk: /storage S3: s3://region@bucket-name Backblaze B2: b2://bucket-name SFTP: sftp://user@host/path Wasabi: wasabi://region@bucket-name
- Local disk: /storage
- S3: s3://region@bucket-name
- Backblaze B2: b2://bucket-name
- SFTP: sftp://user@host/path
- Wasabi: wasabi://region@bucket-name
- Schedule: Set backup frequency (hourly, daily, etc.) - Repository: Path to your data inside the container (e.g., /data)
- Storage: Choose your backup destination: Local disk: /storage S3: s3://region@bucket-name Backblaze B2: b2://bucket-name SFTP: sftp://user@host/path Wasabi: wasabi://region@bucket-name
- Local disk: /storage
- S3: s3://region@bucket-name
- Backblaze B2: b2://bucket-name
- SFTP: sftp://user@host/path
- Wasabi: wasabi://region@bucket-name
- Schedule: Set backup frequency (hourly, daily, etc.) - Local disk: /storage
- S3: s3://region@bucket-name
- Backblaze B2: b2://bucket-name
- SFTP: sftp://user@host/path
- Wasabi: wasabi://region@bucket-name - BorgBackup vs Duplicacy: Which Backup Tool Wins?
- Duplicacy vs Kopia: Which Backup Tool to Self-Host?
- Duplicacy vs Restic: Which Backup Tool to Self-Host?
- Duplicati vs Duplicacy: Backup Tools Compared
- Best Self-Hosted Backup Solutions
- Restic vs Kopia vs BorgBackup
- Duplicati vs Restic
- Kopia vs Restic
- Self-Hosted Alternatives to CrashPlan
- Self-Hosted Alternatives to Backblaze
- Docker Compose Basics
- Reverse Proxy Setup
- Backup Strategy
