Duplicati is a free, open-source backup client that runs in your web browser but stores data locally or on remote servers. It is highly regarded for its block-level deduplication (only saving changed parts of files) and strong AES-256 encryption.

Here is a step-by-step guide to installing and configuring Duplicati for Windows, specifically targeting an SFTP destination.

1. Installation & Initial Launch

1. Download: Go to duplicati.com and download the Windows .msi installer.
2. Install: Run the installer. During setup, you can choose to "Launch Duplicati at startup."
3. Access the UI: Duplicati runs as a background service with a web-based interface.
   • Look for the Duplicati icon in your System Tray (near the clock). Right-click it and select Open.
   • Alternatively, open your browser and go to http://localhost:8200.
4. First Run Tip: On the first launch, it will ask if your machine has multiple users. Usually, you can select "No" to keep it simple, or set a password for the web interface if you want to prevent other people on your PC from changing backup settings.

2. Creating an SFTP Backup Job

Click "Add backup" in the left menu, then select "Configure a new backup" and click Next.

Step 1: General Settings

• Name: Give it a name (e.g., "Work Documents").
• Encryption: Leave it as AES-256 encryption (built-in).
• Passphrase: Create a strong passphrase. Important: If you lose this passphrase, your backups are gone forever. Duplicati cannot reset it for you.

Step 2: Destination (SFTP)

• Storage Type: Select SFTP (SSH) from the dropdown.
• Server: Enter the IP address or hostname of your SFTP server (e.g., 192.168.1.50 or backup.myserver.com).
• Port: Usually 22.
• Path on server: The folder where backups should go (e.g., backups/pc-backup/).
• Username/Password: Enter your SSH credentials.
• Test Connection: Click this button immediately. Duplicati will ask to "Trust the Host Key" (click Yes). If it says "Connection worked," you’re ready to proceed.

Step 3: Source Data

• Browse your local computer and check the boxes for the folders you want to back up (e.g., C:\Users\YourName\Documents).
• Exclusions: You can add filters to skip large, unnecessary files like *.tmp or the Downloads folder.

Step 4: Schedule

• Set how often you want the backup to run (e.g., Daily at 2:00 AM).
• Ensure "Run again if missed" is checked so it catches up if your PC was off during the scheduled time.

Step 5: Options (Retention & Speed)

• Remote Volume Size: The default is 50MB. Leave this as-is unless you have a very fast gigabit connection (then you can increase it to 100MB or 200MB).
• Backup Retention: I recommend Smart backup retention. This keeps:
  • One backup for each of the last 7 days.
  • One backup for each of the last 4 weeks.
  • One backup for each of the last 12 months.
  • This saves massive amounts of space while keeping a long history.

3. Running and Monitoring

• Once saved, you can click "Run now" on the home screen to start the initial backup.
• The first backup will take the longest because it uploads everything. Subsequent backups will be much faster because Duplicati only uploads the "blocks" of data that have changed.

4. How to Restore Files

If you lose a file and need it back:

1. Click Restore in the left sidebar.
2. Select the backup job you want to restore from.
3. Select Files: You will see a file browser. You can pick a specific date/time from the dropdown menu and then check the files/folders you need.
4. Restore Options:
   • Where: Restore to the "Original Location" or a "Target Folder" (safer if you just want to grab one file without overwriting the current one).
   • Permissions: Usually, you can leave these at default.
5. Click Restore, and Duplicati will pull the encrypted blocks from your SFTP server, decrypt them, and place them back on your PC.

Pro-Tips for Duplicati:

• Database Backup: Duplicati keeps a local database of what is on the server to make things fast. Every few months, go to Settings and use the Export feature to save your backup configuration (as a JSON file) to a USB drive or cloud storage. This makes recovering on a brand-new computer much faster.
• Verify: Under "Advanced Options" in your backup job, Duplicati is set by default to verify a small random sample of files after every backup to ensure no data corruption has occurred on the server.