CurseForge · Minecraft mod
JDR's MSB
A sandboxed Luau/Lua 5.1 runtime and studio IDE allowing you to run classic Roblox-style scripts and R6 rigs.
Quick answer
Which JDR's MSB release should I use?
JDR's MSB Public Playtest Release (v1.3.1) targets 1.21.1 with NeoForge. The project page does not say whether this file belongs on the client, dedicated server, or both. No extra mods listed for this file.
Where it goes
Is JDR's MSB required on the client, server, or both?
The project page does not say whether this file belongs on the client, dedicated server, or both.
The source does not explicitly classify this release as client-only or server-only.
What else does JDR's MSB Public Playtest Release (v1.3.1) need?
Public Playtest Release (v1.3.1). Change the file and its required mods may change too.
This file does not list any required mods. Do not add a library just because a different file uses it.
This file does not list any required or optional mods.
Before you install it
Add JDR's MSB without breaking your instance.
Built for JDR's MSB Public Playtest Release (v1.3.1). Pick another file and the loader, install side or required mods may change.
- 01
Stick to this file
Use Public Playtest Release (v1.3.1). It targets 1.21.1 with NeoForge; another release may have different loader, side or dependency requirements.
- 02
Bring the mods it needs
This file does not list any required mods. Do not add a library just because a different file uses it.
- 03
Put it on the correct side
The project page does not say whether this file belongs on the client, dedicated server, or both.
- 04
Pick the file you checked
Use the “Get this file” button beside Public Playtest Release (v1.3.1). It opens that exact file at the source.
About this project
What does JDR's MSB add?
JakeDRavioli's Minecraft Script Builder is an advanced, sandboxed in-game Luau/Lua 5.1 runtime and Roblox-to-Minecraft compatibility engine meant to allow users to run scripts that were originally meant for Roblox on Minecraft.
This mod lets you write, code, and execute Lua scripts on yourself with a direct inspiration from Roblox's layout and coding. Most scripts from Roblox will function exactly like they should on this mod.
Features
Sandboxed In-Game Luau Engine
- This mod is powered by the great work of the ComputerCraft: Tweaked team and their project Cobalt, providing Lua 5.2 implementation into Minecraft.
- Alongside this, this mod codes full native support for standard Roblox classes and data types, such as:
Instance.new(),Vector3,CFrame,Color3,BrickColor,UDim2,NumberSequence,ColorSequence,workspace,Players,TweenService,Debris,SoundService,UserInputService,RunService,HttpService, and many, many more. - This mod also supports bog standard Lua functions like coroutines,
wait(), yielding, and includes Roblox-styled event signals (Changed,ChildAdded,ChildRemoved,InputBegan, etc.).
Full R6 Character Rigging & Animations
- The mod contains full support for joint interpolation, Lerp, and Roblox CFrames. Selectable Rig Modes:
- MC Proportions: R6 anatomy adapted to standard Minecraft player proportions, which supports both Classic and Slim styles.
- Classic R6: 1:1 authentic blocky Roblox player proportions.
- Vanilla Model: Binds animations directly to the Minecraft player skeleton - Which requires making scripts directly for it otherwise it'll look… a little cursed.
- Alongside this, there is also a dummy system implemented which incorporates old Roblox script builder commands (
g/d).
3D World & Mesh Rendering Pipeline
- SpecialMesh & Custom Mesh Parser:
- Native parser for binary Roblox
.mesh(v1.00 and v2.00) formats. - Instant rendering of custom meshes, accessories, and much more.
- Native parser for binary Roblox
- Aesthetic Styles:
- Smooth Mode: High-fidelity UV spheres, smooth cylinders, and continuous wedge slopes, emulating Roblox in its entirety.
- Voxel Mode: Transforms wedges into authentic Minecraft voxel stairs and spheres/cylinders into stepped voxel forms - Giving a more minecraft-styled emulation.
- Additive/translucent alpha blending, lifetime scaling, texture mapping, and physics drag for Trails and ParticleEmitters.
- ScreenGuis and BillboardGuis are also entirely implemented - With Fonts also being imported (which are found via Google Fonts.)
3D Spatial Audio System
- Full 3D directional audio with
PlaybackLoudnessextraction, pitch modulation, volume scaling, and distance attenuation. - Bundled sound library with support for online asset streaming where available.
In-Game Studio IDE & Script Hub
Press your bound menu key to open the full modern UI:
- Script Hub: Load in your own scripts from wherever you find them and easily load & run them on the fly.
- Code Editor: Live syntax highlighting, line numbers, and snippets available.
- Workspace Explorer: Live DOM tree hierarchy inspection of all active instances, parts, and properties.
- Live Console: Real-time Lua print outputs, warnings, error stack traces, and FPS/render statistics.
- Moveset & Audio Decks (WIP): Keybind management for scripts & sound preview panel to view downloaded assets.
Security & Sandbox Disclosures
All scripts run strictly within the Cobalt JVM interpreter. Scripts cannot invoke OS commands, execute shell binaries (os.execute and io.popen are removed), access the host filesystem outside the game directory, or load native C libraries. Alongside this, script execution permissions are restricted to authorized players on dedicated servers, requiring /op.
Third-Party Libraries & Acknowledgments
This mod builds upon and integrates the following open-source technologies:
- Cobalt by SquidDev & the CC: Tweaked Team (Lua 5.1 / Luau VM for Java) - Licensed under MIT.
- Google Fonts: Fonts provided for the project come from here.
- Roblox API Specifications & Asset Formats: Inspiration for the DOM and math structures (
CFrame,Vector3,Motor6D).
Project description from CurseForge.
Pick your setup
JDR's MSB by Minecraft version and loader
Choose the version and loader you play, then open the matching release.
Check the dependencies, then try the file in a copied instance before changing a world you care about.
Recent files
JDR's MSB versions and loaders
Public Playtest Release (v1.3.1)
scriptbuilder-1.3.1.jar
4 Sept 2026
Looking for an older file? The official CurseForge project page is in Resources.