Do I need Fabric API to use this mod?

Yes, you need both Fabric Loader and Fabric API installed. The mod won't work without Fabric API.

What's the difference between de-sync and close without packet?

De-sync closes your GUI on the server but keeps it open on your client. Close without packet just closes your GUI locally without the server knowing.

Can I use this on multiplayer servers?

Technically yes, but be careful. Some servers might flag this as suspicious since it manipulates packets. Use it on servers you own or have permission on.

How do I know what Sync Id and Revision to use when fabricating packets?

The mod displays both values in your current GUI when you open any container. Just look at the display and copy those numbers into the packet fabricator.

What's the difference between ClickSlotC2SPacket and ButtonClickC2SPacket?

ClickSlotC2SPacket is sent when clicking items in containers. ButtonClickC2SPacket is sent when clicking buttons in server-side GUIs like enchantment screens.

UI Utils Mod (1.19.4, 1.19.2) – Advanced Inventory and Packet Control

UI Utils Mod is a Fabric mod that gives you control over your inventory interactions and network packets. It’s built for players who want to dig into the technical side of how Minecraft handles GUIs and packet stuff. If you’re testing server mechanics or learning about client-server sync, this mod gives you the tools to experiment.

What Can You Do With UI Utils Mod?

Close Without Packet – Close your current GUI without telling the server
De-sync Mode – Keep your GUI open on your client while closing it server-side, great for testing sync behavior
Packet Control – Toggle whether click and button packets get sent to the server
Delay Packets – Store all your clicks and send them together later
Save GUI – Save your current GUI state and pull it up anytime with a hotkey
Disconnect and Send – Blast all your stored packets to the server and disconnect immediately
Sync ID Display – See the sync numbers used for GUI packets
Fabricate Packets – Build custom ClickSlot and ButtonClick packets in a dedicated window

How to Use the Mod

Open any inventory or container and you’ll see the utility buttons. Here’s what they do:

Basic Controls

Close without packet – Closes your GUI without notifying the server
De-sync – Closes your GUI server-side only, client-side stays open
Send packets – Turn this on or off to control whether packets get sent
Delay packets – When on, packets get stored instead of sent immediately
Save GUI – Saves your current GUI state to access later
Disconnect and send packets – Sends all delayed packets and disconnects

Creating Custom Click Slot Packets

ClickSlotC2SPacket is what gets sent when you click a slot. Here’s how to make a custom one:

Click the “Fabricate packet” button
Select “Click Slot”
Enter the Sync Id and Revision from your GUI
Set the Slot number you want to interact with (starts at 0)
Configure Button: 0 for left-click, 1 for right-click, 0-8 for hotbar slots, 40 for offhand
Choose Action: PICKUP, QUICK_MOVE, SWAP, CLONE, THROW, QUICK_CRAFT, or PICKUP_ALL
Click Send to execute

Creating Custom Button Click Packets

ButtonClickC2SPacket is sent when clicking buttons in server GUIs. To use it:

Click “Fabricate packet” and select “Button Click”
Enter the Sync Id from your GUI
Set the Button Id (starts at 0)
Click Send

Requirements

You’ll need:

Installation

Download and install Fabric Loader for your Minecraft version
Download Fabric API and place it in your mods folder
Download UI Utils Mod from the links below
Place the .jar file into your Minecraft mods folder
Launch Minecraft with the Fabric profile

UI Utils Mod 1.19.4 & 1.19.2 – Inventory & Packet Control

UI Utils Mod (1.19.4, 1.19.2) – Advanced Inventory and Packet Control

What Can You Do With UI Utils Mod?

How to Use the Mod

Basic Controls

Creating Custom Click Slot Packets

Creating Custom Button Click Packets

Requirements

Installation

Download Links

For Minecraft 1.19.2

For Minecraft 1.19.3

For Minecraft 1.19.4

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