JSCore
by Fabric Core
JSCore lets players and modders write JavaScript that extends the game, with a module system, a package manager and access to Minecraft classes.
What it does
JSCore is a JavaScript runtime for Minecraft that works in a similar way to KubeJS. Scripts start from an init.js file, and the runtime offers Node.js style features such as console.log and fs, along with declarative command registration for adding commands. Scripts can create commands, menus and toggles, and they can interact with other mods.
Because JSCore is a thin wrapper around the Fabric modding API, nearly everything Fabric allows can be reached from a script, except Mixins. Classes in the net.minecraft package are accessible, and Yarnwrap maps their obfuscated names to readable names so scripts can refer to them by the real name. Additional features come from third-party modules listed in the package repository, which anyone can publish to.
JSCore is a Fabric-only mod with Fabric API and Yarnwrap as required dependencies. It is client-side only, so servers do not need it, and it is open source under the GNU Affero General Public License v3.0 or later. Files cover 1.21 – 1.21.10 across 11 release versions, and the latest Fabric file is 0.2.0.17 for 1.21.10, a beta build.
Key features
Scripted game extensions
Scripts can add commands, menus and toggles, and extend the game in many other ways without writing a full Java mod.
Node.js style module system
Complex game mechanics can be split into small, manageable modules that are loaded and combined in a script.
Command registration
Commands are registered declaratively, so a script describes what a command does rather than wiring up each step by hand.
Access to Minecraft classes
Classes from the net.minecraft package can be used directly, with Yarnwrap supplying readable names in place of obfuscated ones.
Third-party module packages
A package manager installs modules from a shared repository, where anyone can publish packages for others to use.
Gallery
Compatibility
Latest build for each game version and loader.
1.21.x11 of 11 versions with builds
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 2
How it compares
JsScripts is a Fabric mod for 1.21.8 – 26.1.1 that runs on client and server, and it is released under All rights reserved. BrickItem is a server-side only Fabric mod for 1.21.11 under the MIT License. Declarative UI is a server-side only Fabric mod for 1.21.11 – 26.3 under the GNU Lesser General Public License v3.0 only, and it is open source. JSCore differs from all three by being client-side only and by its scripting approach.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| JSCore | Fabric | 1.21 – 1.21.10 | Client-side only | 2025-11-17 |
| JsScripts | Fabric | 1.21.8 – 26.1.1 | Client and server | 2026-04-01 |
| BrickItem | Fabric | 1.21.11 | Server-side only | 2026-02-20 |
| Declarative UI | Fabric | 1.21.11 – 26.3 | Server-side only | 2026-09-30 |
Questions
Does JSCore need Fabric API?
Does a server need JSCore?
Which Minecraft versions does JSCore support?
In the catalog
JSCore is one of 3,514 Library mods on ModsFinder, and one of 2,348 Library mods for Fabric. 15,569 mods support Minecraft 1.21.10.
Similar mods
What the author says
JSCore is a thin wrapper around FabricMC. This mod provides full JavaScript support for Minecraft modding, you can create or use community modules to customise your game.
Official listing
- Modrinth page
- modrinth.com/mod/jscore
- Owner
- Fabric Core
- Published
- 2025-01-28
- Updated on Modrinth
- 2025-11-17
- Facts verified
- 2026-10-15