Sync Client Server (SCS)

Sync Client Server (SCS) is a mod designed to keep client mods and configurations synchronized with a server-provided modpack, reducing version mismatches and manual mod management.

With a single in-game Update button directly in the multiplayer server list, players can download the mods and configs required by the server in a simple and reliable way.

📸 Preview

In-game printscreen

🎯 Goal

SCS aims to simplify server administration and improve player experience by making modpack updates clear, predictable, and user-friendly, without requiring external launchers or manual file management.

✨ What SCS Can Do

In-game Update button in the multiplayer server list
Confirmation screen with update summary and Clear cache option
modId-based synchronization to prevent duplicated or outdated mods
Optional synchronization of /config alongside /mods
Optional mirror mode for /mods and /config
Server-enforced removal of specific client mods
Per-server isolated cache
Built-in lightweight file server to host mods.zip and config.zip

⚠️ Important:

Mod updates require a game restart to take effect

Config updates do NOT require a restart and are applied immediately

🎮 Client Usage (Simple & Automatic)

The client workflow is intentionally minimal.

1️⃣ Add the server

Add the server normally in the Multiplayer screen
The Download URL field is automatically filled using the server address and port
You may override it manually if needed

Example:

http://myserver.com:25566

2️⃣ Update the client

Select the server in the list
Click Update
Review the summary and confirm

That’s it.
Restart the game only if mods were updated.

🧹 Clear Cache

Use Clear cache from the confirmation screen if:

A download fails
The client becomes out of sync
ZIP contents changed but no update is triggered
Other unexpected behaviors

Cache is isolated per server and safe to clear.

🖥️ Server Usage (Admin Guide)

1️⃣ Install and start

Install SCS on the server
Start the server once to generate the config file

2️⃣ Common Configuration

Config file:

config/scs-common.toml

Default values:

fileServerPort = 25566
updateConfig = true
mirrorMods = false
mirrorConfig = false

Explanation:

fileServerPort
Port used by the built-in file server (default: 25566)
updateConfig
Enables client config updates (enabled by default)
mirrorMods / mirrorConfig
Disabled by default. When enabled, client folders are forced to exactly match the ZIP files

Because updateConfig is enabled by default, server admins can push new configuration changes to clients, such as enabling or disabling mirror options.

3️⃣ Creating the update packages

Option A: Using in-game commands

On the server, run:

/scs save-mods
/scs save-config

This generates:

mods.zip
config.zip

Option B: Manual ZIP creation (advanced / recommended for control)

Admins may manually create or edit:

mods.zip
config.zip

This allows:

Shipping only specific mods or configs
Full control over update contents

Both methods are fully supported.

4️⃣ Removing client mods (server-enforced)

To force the removal of specific client mods:

Create a file named:

modsToRemoveFromTheClient.json

Place it inside mods.zip
List the .jar filenames to remove

Example:

[
  "examplemod1.jar",
  "examplemod2.jar"
]

These mods will be deleted from the client during the update.

5️⃣ Built-in File Server

When the server is running, SCS automatically hosts:

mods.zip
config.zip

On:

<server-ip>:fileServerPort

Default:

<server-ip>:25566

No external web server is required.

📦 Modpack Usage

Feel free to include this mod in your modpack — credits are appreciated but not required.

❤️ Credits & Fork Notice

This project is a fork of the mod MMMMM by Place-Boy.
Original project: https://www.curseforge.com/minecraft/mc-mods/mmmmm

All credit for the original concept and foundation goes to the original author.