FolderSyncr

FolderSyncr is a .NET 10 WPF folder comparison and synchronization tool for Windows. It follows the proven compare-first workflow used by tools like FreeFileSync: choose two folders, compare them, review the planned operations, then synchronize.

FolderSyncr is an independent project and is not affiliated with FreeFileSync.

See the tool documentation for screenshots and usage details.

Features

• Compare two folders before changing anything.
• Preview left-to-right copies, right-to-left copies, deletes, equal files, and conflicts.
• Synchronization modes:
  • TwoWay
  • MirrorLeftToRight
  • MirrorRightToLeft
  • UpdateLeftToRight
  • UpdateRightToLeft
  • Custom rule matrix
• Custom synchronization rules for left-only, right-only, newer, and same-time-different files.
• Compare by file time/size or SHA-256 content hash.
• Configurable file time tolerance for time/size comparisons.
• Optional binary verification after copying files.
• Deletion handling options: permanent delete, recycle bin, or timestamped versioning folder.
• Versioning modes for replace, timestamped folders, and file-time names.
• Lock files prevent concurrent sync jobs from writing the same folder pair.
• Built-in sample data generator for first-run testing.
• Drag-and-drop folder selection for left and right paths.
• Per-row checkboxes to include or exclude planned sync actions.
• Result-grid double-click plus context menu actions for opening items, copying relative paths, and include/exclude filters.
• Volume-label paths like [Backup-Disk]\folder and volume GUID paths like \\?\Volume{01234567-89ab-cdef-0123-456789abcdef}\folder for removable drives.
• UNC paths like \\server\share\folder and extended UNC paths like \\?\UNC\server\share\folder, with clear unavailable-share errors.
• SFTP roots such as sftp://user:password@example.com/backups for comparing, copying, and permanently deleting remote files.
• FTP roots such as ftp://user:password@example.com/backups, with anonymous FTP when no credentials are supplied.
• Configurable remote connection/channel count and optional SFTP compression.
• Optional Volume Shadow Copy fallback for reading locked local files.
• Optional one-hour daylight-saving-time shift ignore for time/size comparisons.
• Include and exclude wildcard filters.
• Import FreeFileSync .ffs_gui, .ffs_batch, and .ffs_real configurations.
• Edit multiple folder pairs in the WPF UI.
• Export supported settings to FreeFileSync-compatible .ffs_gui files.
• Import FreeFileSync JSON results and log files.
• Store local sync run history as FreeFileSync-like JSON.
• Maintain a hidden sync.ffs_db-style two-way sync database in each synchronized root.
• Detect moved files from the sync database and show linked move hints in the preview.
• Run saved configurations unattended with FolderSyncr.Cli, FreeFileSync-like exit codes, and JSON output.
• Save, open, and reload native .foldersyncr.json configurations.
• Expand environment variables in folder paths.
• Expand date/time macros in folder paths.
• Expand common Windows special-folder macros in folder paths.
• Conflict detection when files differ, neither side is clearly newer, or both sides changed since the last two-way sync.
• Cancellable compare and synchronization operations.
• FreeFileSync-inspired layout with configuration list, overview pane, split file grids, action column, and statistics bar.
• Light and dark mode toggle.

Requirements

• Windows 10 or newer
• .NET 10 SDK

Check your installed SDKs:

dotnet --list-sdks

Build

dotnet build .\FolderSyncr.slnx

Test

dotnet test .\FolderSyncr.slnx

Release Builds

When a GitHub release is published, the release workflow builds FolderSyncr.exe and FolderSyncr.Cli.exe for win-x64, applies the release tag as the application version, creates a ZIP, and uploads it to the release assets.

Recommended release tag format:

v1.2.3

The uploaded asset is named like:

FolderSyncr-v1.2.3-win-x64.zip

Run

dotnet run --project .\FolderSyncr\FolderSyncr.csproj

Open a configuration at startup:

dotnet run --project .\FolderSyncr\FolderSyncr.csproj -- .\Backup.foldersyncr.json

Override the left and right folders at startup:

dotnet run --project .\FolderSyncr\FolderSyncr.csproj -- .\Backup.foldersyncr.json -dirpair C:\Source D:\Target

Start the WPF app minimized:

dotnet run --project .\FolderSyncr\FolderSyncr.csproj -- .\Backup.foldersyncr.json --minimized

Run a saved configuration unattended:

dotnet run --project .\FolderSyncr.Cli\FolderSyncr.Cli.csproj -- .\Backup.foldersyncr.json --json .\result.json

FolderSyncr.Cli writes the run result JSON to stdout, optionally writes the same JSON to --json <path>, exits automatically after the unattended run, and returns 0 for success, 1 for warnings, 2 for errors, or 3 for cancellation. Pass multiple configuration files to merge their folder pairs into one in-memory batch run, and optionally include a FreeFileSync GlobalSettings.xml file for supported global options. Add --dry-run to compare without applying changes, --watch --idle <seconds> for realtime monitoring, --var NAME=VALUE for temporary run-scoped variables, --error-handling show|ignore|cancel to control per-item sync errors, --symbolic-links skip|follow|copy to control symbolic links, --connections <count> to run file operations in parallel, --sftp-compression to prefer SFTP compression, and --volume-shadow-copy to read locked local files through VSS.

When a native or imported FreeFileSync configuration contains multiple preserved folder pairs, FolderSyncr.Cli processes every pair in one run and applies local per-pair filters when present. Passing a single -dirpair <left> <right> override runs only that overridden pair.

For service-style usage, run FolderSyncr.Cli from Windows Task Scheduler at logon, on a schedule, on workstation unlock, or on idle. Use the WPF app with --minimized only when a user should still be able to review the session interactively.

How To Use

The short version is: choose two folders, click Compare, review the preview, then click Synchronize.

For the full walkthrough, see docs/USER_GUIDE.md.

For the MTP/portable-device implementation investigation, see docs/MTP_SUPPORT_INVESTIGATION.md.

Filters

Filters follow the FreeFileSync wildcard syntax. Use | or new lines between items; FolderSyncr also accepts semicolons and commas for older native configurations. Folder rules match all descendant files.

Examples:

*.txt | *.md

bin\ | obj\ | .git\

External Commands

Use Tools -> External commands to add row context-menu commands such as Explorer, clipboard, or WinMerge actions. Press 0 through 9 to run configured commands for selected rows. Commands support FreeFileSync-style item macros including %item_path%, %local_path%, %item_name%, %parent_path%, opposite-side suffix 2, and selected-item-list suffix s.

Project Structure

FolderSyncr/
  Models/       File comparison and operation models
  Services/     Filtering, comparison, and synchronization engine
  ViewModels/   WPF view models and commands
  MainWindow.*  Main WPF interface

Safety Notes

FolderSyncr previews operations before it writes files. Still, synchronization tools can copy, overwrite, and delete data depending on the selected mode. Test with disposable folders before using it on important files.

License

FolderSyncr is licensed under the MIT License. See LICENSE.