
DemoBox
A tool for creating interactive demo environments for mods
About this Mod
DemoBox
DemoBox is a tool for creating interactive demos for mods, originally created for BlanketCon '23.
It uses plasmid, the library behind nuceleoid games, to manage virtual worlds safely,
allowing users to experience mods in survival mode without risking them breaking things in the overworld.
Usage
To create a demo using demobox, first build a structure and store it with a structure block.
This structure will spawn in your demo worlds centered at 0, 0.
As of 26.1, demos are first created using the /demo create command. This command opens a dialog letting your configure the demo.
You can then use /demo open to open it, or /demo edit to modify it.
Editing demos requires the demobox.edit command. This should not be given to untrusted players,
as it permits them to run arbitrary commands with gamemaster permissions. Opening demos requires the demobox.open permission.
This one can generally be given to untrusted players unless you want to keep some demos inaccessible.
Demos can also be attached to signs using the /demobox sign command. It overwrites the content the targeted sign with a link to the demo.
Using the command requires the demobox.sign permission, but interacting with the sign itself doesn't require anything.
All commands except /demobox leave default to gamemaster/level 2 permissions unless their specific nodes are set.
Pre 26.1 instructions
Then you can run the /demobox open <structure> command to visit a demo world.
You can leave using the /demobox leave command or by using the /game command from plasmid.
The open command requires a permission level of 2 or the demobox.open permission node
because it can be used to create dimensions with arbitrary structures and that could cause problems.
The recommended way to give players access to demos is by using signs with click events.
The open command also accepts a position for where players spawn and a function to run during setup if you need to do something more advanced.
Available Versions
How to Install DemoBox on Your Server
Order Server
Order a Minecraft Java server with at least 3 GB RAM (4 GB recommended).
Set fabric Loader
In the panel under "Egg", select the fabric loader and matching Minecraft version (26.1).
Install Mod
Open the mod browser in the dashboard and search for "DemoBox". Click "Install" – done! Alternatively, upload the .jar via SFTP to the /mods folder.
Compatibility
Mod Loaders
Minecraft Versions
26.1, 1.21.8, 1.21.1 (+2 more)
Server-side
✓ RequiredRecommended RAM
4 GB(min. 3 GB)Frequently Asked Questions
DemoBox server crashes on startup – what to do?
Most common cause: wrong fabric version or insufficient RAM. Check the server log (latest.log) for "OutOfMemoryError" or "Mixin" errors. With Mado Hosting: ensure at least 3 GB RAM is allocated and the loader matches the mod version (26.1). You can switch loaders with one click in the panel.
Is DemoBox compatible with fabric and quilt?
DemoBox officially supports fabric, quilt for Minecraft 26.1, 1.21.8, 1.21.1. The Mado dashboard automatically detects incompatible loader combinations.
Server lagging with DemoBox – how to optimize performance?
Recommended RAM: 4 GB (per 8 players). Use /spark profiler to check if DemoBox consumes the most tick time. Common fixes: reduce server view-distance to 8-10, install "performant" or "starlight" as supplementary mods on Forge. With Mado Hosting, your server runs on NVMe SSDs with dedicated CPU cores for minimal latency.
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Rent Modded Server
Install DemoBox with just one click on your server.