Hollow Sync

An application for Hollow Knight and Hollow Knight: Silksong that lets you transfer your progress between PC and Nintendo Switch.

Prefer command line? Check out the CLI version for terminal based usage.

Important

This tool requires homebrew on your Switch. Always backup your saves before using. Use at your own risk.

Requirements

• Windows 10 or newer
• Hollow Knight or Silksong installed on Windows
• Homebrew-enabled Nintendo Switch
• JKSV installed on your Switch

Installation

Option 1: Pre-built App (Recommended)

1. Download the latest release from the Releases page
2. Run the installer (.exe file)
3. Launch "Hollow Sync" from your Start menu

Option 2: Build from Source

# Clone the repository
git clone https://github.com/ArixAR/hollow-sync.git
cd hollow-sync

# Install dependencies
npm install

# Run in development mode
npm run tauri dev

# Or build for production
npm run tauri build

How to Use

Step 1: Setup

• Open the Hollow Sync app
• The app automatically scans for both Hollow Knight and Silksong saves
• Switch between games using the toggle at the top
• Select your save slot from the detected characters

Step 2: Sync Saves

• Click "Sync to Switch" to prepare your PC save for Switch
• Click "Sync to PC" to prepare your Switch save for PC
• The app shows save timestamps to help avoid conflicts

Step 3: Transfer to Switch

1. Insert your Switch SD card into your PC
2. Copy the generated backup folder to the appropriate JKSV folder:
   • Hollow Knight: /JKSV/Hollow Knight/
   • Silksong: /JKSV/Hollow Knight Silksong/
3. Use JKSV on Switch to restore the backup from the folder

JKSV Error: "Backup contains no meta file!"

If JKSV returns an error about missing .nx_save_meta.bin or the save doesn't appear after restore, follow this workaround:

1. On your Switch: Start a new game in Hollow Knight/Silksong and play until it creates a save file
2. Create JKSV backup: Open JKSV, select the game, and create a backup of this new save
3. Copy to PC: Copy the JKSV backup ZIP file to your PC
4. Replace save data: Open the ZIP file and replace the user1.dat file inside with your PC save (the decrypted save from this tool)
5. Copy back to Switch: Copy the modified ZIP back to the JKSV folder on your Switch's SD card
   • Hollow Knight: /JKSV/Hollow Knight/
   • Silksong: /JKSV/Hollow Knight Silksong/
6. Restore: In JKSV, select the modified backup and choose "Restore"

Why this works: This ensures the backup contains the required .nx_save_meta.bin metadata file while using your actual PC save data.

Alternative: Automatic Cloud Sync

For a more automated approach, you can set up JKSV to sync directly with cloud storage instead of manually transferring files via SD card.

Setup: Configure automatic cloud backups using either:

• Google Drive
• WebDAV

Once cloud sync is configured:

1. Point the app to your cloud folder path in settings
2. Use the sync buttons normally - the app will handle cloud files
3. Changes automatically sync across both platforms

Benefits: No more SD card removal, automatic backups, and seamless syncing once configured.

Note: You still need this app for format conversion since PC and Switch use different save file formats.

Save Locations

PC:

• Hollow Knight: C:\Users\[Username]\AppData\LocalLow\Team Cherry\Hollow Knight\
• Silksong: C:\Users\[Username]\AppData\LocalLow\Team Cherry\Hollow Knight Silksong\[UserID]

Switch (JKSV folders):

• Hollow Knight: /JKSV/Hollow Knight/
• Silksong: /JKSV/Hollow Knight Silksong/

Troubleshooting

Can't find saves? Make sure you've played Hollow Knight or Silksong and saved at least once.

App won't start? Check that you're running Windows 10 or newer.

Sync not working? Verify the output folder exists and you have write permissions.

Switch issues? Check that JKSV is installed and you're using the exact SD card path.

Advanced: Switch 1 → Switch 2 Save Migration

If you want to move your Hollow Knight or Silksong saves directly from Switch 1 to Switch 2, this requires additional steps beyond the normal PC ↔ Switch sync.

Warning: This process is advanced and carries risk. Only attempt if you fully understand the implications.

See the full guide here: Switch Save Transfer Guide