How to Sync Two Folders in Real Time in Windows 11 and 10

You want to sync two folders in real time in Windows 11 or 10, but Windows doesn’t include a general tool for mirroring arbitrary folders. FreeFileSync is the strongest free option, while DSynchronize offers a smaller portable alternative.

Fix #1: Sync folders with FreeFileSync and RealTimeSync

FreeFileSync handles the file comparison and copying. Its included RealTimeSync tool watches for changes and runs your saved sync job automatically.

Back up important files before starting. A mirror or two-way job can copy accidental deletions to the other folder.

1. Download FreeFileSync from its official website.
2. Run the installer.
3. Open FreeFileSync after installation. You should see left and right folder panels.
4. Select the left folder you want to sync.
5. Select the destination in the right panel.

For a NAS, enter its UNC path, such as \\\\NAS\Backup\Work. UNC paths are more dependable than mapped drive letters, especially after restarting Windows.

6. Click the synchronization settings button.
7. Choose the mode that matches how you use the folders:

Sync mode	What it does	Best use
Two way	Copies changes in both directions	Working from either folder
Mirror	Makes the destination match the source, including deletions	Maintaining an exact replica
Update	Copies new and changed files without removing destination files	Lower-risk copying and archiving

I’d start with Update unless you need exact mirroring. It reduces the chance that an accidental source deletion removes the destination copy.

8. Click Compare to preview the planned changes. Check the direction arrows and confirm that the correct files will be copied.
9. Click Synchronize to run the first job. Wait until FreeFileSync reports that synchronization completed successfully.
10. Save the configuration as a batch job using the Save as batch job option. You should receive an .ffs_batch file.
11. Open RealTimeSync, which is installed with FreeFileSync.
12. Drag the saved .ffs_batch file into the RealTimeSync window. The watched folders and sync command should appear.
13. Set a delay if you don’t want every rapid file change to trigger a separate run.
14. Click Start. RealTimeSync should remain active and watch the configured folders.

Create, rename, and edit a test file in the source. The change should reach the destination after the configured delay. So far, so good means testing deletions too, but only with disposable files.

RealTimeSync must remain running. If you close it, folder monitoring stops.

Fix #2: Sync folders with DSynchronize

DSynchronize is a portable Windows utility with real-time monitoring, filters, bidirectional syncing, and service support. Its interface is more technical than FreeFileSync, but the small download and lack of an installer make it a promising choice for a dedicated sync task.

1. Open the DSynchronize page on Softpedia (the developer’s own site is no longer online).
2. Download its ZIP archive.

4. Extract the ZIP archive to a permanent folder, such as C:\Tools\DSynchronize.
5. Open the extracted folder.
6. Run the DSynchronize executable. The main window should show source, destination, and synchronization options.

Don’t run the program directly from the ZIP archive. DSynchronize needs access to its accompanying files and must remain in a stable location if you configure autostart.

7. Add an entry to the source list using its context menu or add control. The exact label and placement can vary by DSynchronize version.
8. Browse to the folder containing the files you want to copy.
9. Confirm the selected source path.

10. Add an entry to the destination list.
11. Browse to the local folder, USB drive, shared folder, or NAS location that will receive the files.
12. Confirm the destination path. Both paths should now appear as a matched pair.

Double-check the direction before continuing. Selecting the folders backward can copy old files over newer ones.

13. Enable Bidirectional synchronization only if changes from either folder must reach the other.
14. Enable the option that creates missing folders if you want new subfolders copied automatically.
15. Configure Backup Changes if you want DSynchronize to retain earlier versions.
16. Open the filter settings if you need to exclude cache folders, temporary files, or specific file types.

17. Leave real-time monitoring disabled for the first run.
18. Click Synchronize.
19. Review the log after the initial copy finishes. It should list the files added, updated, or skipped.

20. Create a disposable file in the source folder.
21. Run Synchronize again.
22. Confirm that the test file appears at the destination.
23. Enable Realtime sync under the timer or special options. DSynchronize should begin monitoring without another manual run.

DSynchronize must remain open unless you configure its service mode. You can minimize it while testing.

Fix #3: Start DSynchronize automatically as a service

Service mode keeps DSynchronize running in the background, including when nobody is signed in. Administrator access is required to install the service.

1. Close DSynchronize.
2. Right-click its executable.
3. Select Run as administrator.
4. Approve the User Account Control prompt. DSynchronize should reopen with elevated permissions.

5. Enable Autostart in DSynchronize.
6. Enable Autostart as service.
7. Select the service installation control when prompted. Its wording or placement can vary between releases.

8. Start the installed service.
9. Confirm that DSynchronize reports the service as running.

10. Close the DSynchronize window.
11. Create another disposable file in the source folder.
12. Confirm that the file reaches the destination while the main window is closed.

A service running under the Windows system account can have trouble accessing NAS shares. If local folders sync but the NAS doesn’t, run the service under a Windows account that has permission to the share, or keep DSynchronize running inside that signed-in account.

Fix #4: Check why real-time sync isn’t updating files

Use these checks when changes stop reaching the destination.

1. Confirm that RealTimeSync, DSynchronize, or the DSynchronize service is running.
2. Verify that the configured source and destination paths still exist.
3. Reconnect any USB drive used as the destination.
4. Confirm that the NAS or other computer is powered on and reachable.
5. Replace an unreliable mapped drive letter with a UNC path such as \\\\\\server\share.
6. Check that your Windows account can create and delete a test file in the destination.
7. Run the sync tool as administrator if either folder is protected by Windows.
8. Review the application’s log for access errors, missing paths, or locked files.
9. Allow the initial full synchronization to finish before judging real-time performance.

For a large media library or project folder, exclude temporary directories and caches. Folders that change thousands of files continuously may work better with a scheduled job than constant monitoring.

Other real-time folder sync options

Setting up Windows Hello can improve security, but for real-time sync, FreeFileSync and DSynchronize are more relevant. AOMEI Backupper offers a guided interface and combines backup with folder synchronization, but real-time sync requires an upgraded edition. GoodSync is a paid option with versioning, encryption, and business-focused controls.

OneDrive works well when your goal is cloud access across Windows PCs. It doesn’t provide general real-time mirroring between any two arbitrary local, USB, or NAS folders.

Avoid building a new setup around SyncToy. It isn’t maintained for current Windows installations, while FreeFileSync and DSynchronize support Windows 10 and Windows 11 workflows.

When the fixes don’t work

Test the same job with two small local folders. If local syncing works, the original destination has a permission, connection, or storage problem. Repeated read errors, disappearing drives, or corrupted files warrant checking the USB drive, SSD, or NAS before trusting it with another copy.

Conclusion

Fix #1, using FreeFileSync with RealTimeSync, usually gives the best balance of control and clear previews. DSynchronize is worth trying for a lightweight service, but recurring file errors or disconnects point to the destination drive or network rather than the sync software.