##### v4 • minecraft‑java‑core
!stable version

minecraft‑java‑core is a NodeJS/TypeScript solution for launching both vanilla and modded Minecraft Java Edition without juggling JSON manifests, assets, libraries or Java runtimes yourself. Think of it as the core of an Electron/NW.js/CLI launcher.

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Need help or just want to chat? Join the community Discord!

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``bash
npm i minecraft-java-core


or


yarn add minecraft-java-core
`

Requirements: Node ≥ 18, TypeScript (only if you import .ts), 7‑Zip embedded binary.

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`ts
const { Launch, Microsoft } = require('minecraft-java-core');
const launcher = new Launch();

const fs = require('fs');
let mc

(async () => {
if (!fs.existsSync('./account.json')) {
mc = await new Microsoft().getAuth();
fs.writeFileSync('./account.json', JSON.stringify(mc, null, 4));
} else {
mc = JSON.parse(fs.readFileSync('./account.json'));
if (!mc.refresh_token) {
mc = await new Microsoft().getAuth();
fs.writeFileSync('./account.json', JSON.stringify(mc, null, 4));
} else {
mc = await new Microsoft().refresh(mc);
fs.writeFileSync('./account.json', JSON.stringify(mc, null, 4));
if (mc.error) process.exit(1);
}
}

const opt = {
url: "https://luuxcraft.fr/api/user/48c74227-13d1-48d6-931b-0f12b73da340/instance",
path: './minecraft',
authenticator: mc,
version: '1.8.9',
intelEnabledMac: true,
instance: "Hypixel",

ignored: [
"config",
"logs",
"resourcepacks",
"options.txt",
"optionsof.txt"
],

loader: {
type: 'forge',
build: 'latest',
enable: true
},
memory: {
min: '14G',
max: '16G'
},
};

launcher.Launch(opt);
launcher.on('progress', (progress, size) => console.log([DL] ${((progress / size) * 100).toFixed(2)}%));
launcher.on('patch', pacth => process.stdout.write(pacth));
launcher.on('data', line => process.stdout.write(line));
launcher.on('error', err => console.error(err));
})();
`

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Documentation

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| Function | Type | Description |
|----------|---------|------------------------------------------------------------------------|
| launch | Promise | Launches Minecraft with the given LaunchOptions (see below). |

#### LaunchOptions

| Parameter | Type | Description | Required |
|-----------|------|-------------|----------|
| path | String | Working directory where game files are stored (usually .minecraft). | ✔︎ |
| url | String \| null | Custom version manifest base URL (only for mirror setups). | — |
| authenticator | Object | Microsoft / Mojang / AZauth profile returned by the authenticator. | ✔︎ |
| timeout | Integer | Network timeout in milliseconds for downloads. | — |
| version | String | 'latest_release', 'latest_snapshot', '1.21.1'. | — |
| instance | String \| null | Name of the instance if you manage multiple profiles. | — |
| detached | Boolean | Detach the Java process from the launcher. | — |
| intelEnabledMac | Boolean | Force Rosetta when running on Apple Silicon. | — |
| downloadFileMultiple | Integer | Max parallel downloads. | — |
| loader.enable | Boolean | Whether to install a mod‑loader (Forge/Fabric/…). | — |
| loader.type | String \| null | forge, neoforge, fabric, legacyfabric, quilt. | — |
| loader.build | String | Loader build tag (e.g. latest, 0.15.9). | — |
| loader.path | String | Destination folder for loader files. Defaults to ./loader. | — |
| mcp | String \| null | Path to MCP configuration for legacy mods. | — |
| verify | Boolean | Verify SHA‑1 of downloaded files. | — |
| ignored | Array | List of files to skip during verification. | — |
| JVM_ARGS | Array | Extra JVM arguments. | — |
| GAME_ARGS | Array | Extra Minecraft arguments. | — |
| java.path | String \| null | Absolute path to Java runtime. | — |
| java.version | String \| null | Force a specific Java version (e.g. 17). | — |
| java.type | String | jre or jdk. | — |
| screen.width | Number \| null | Width of game window. | — |
| screen.height | Number \| null | Height of game window. | — |
| screen.fullscreen | Boolean | Start the game in fullscreen mode. | — |
| memory.min | String | Minimum RAM (e.g. 1G). | ✔︎ |
| memory.max | String | Maximum RAM (e.g. 2G). | ✔︎ |

> Recommendation: Start with the minimal set (authenticator, path, version, memory) and gradually add overrides only when you need them.

#### Default configuration

Below is the complete default LaunchOptions object returned by
minecraft‑java‑core when you don’t override any field. Use it as a quick
reference for every available parameter and its default value.
(Parameters marked nullable can be left null/undefined and the library
will figure out sane values.)

`ts
const defaultOptions = {
url: null, // Optional custom manifest URL
authenticator: null, // Microsoft/Mojang/AZauth profile
timeout: 10000, // Network timeout in ms
path: '.Minecraft', // Root directory (alias: root)
version: 'latest_release', // Minecraft version (string or 'latest_…')
instance: null, // Multi‑instance name (optional)
detached: false, // Detach Java process from parent
intelEnabledMac: false, // Rosetta toggle for Apple Silicon
downloadFileMultiple: 5, // Parallel downloads

loader: {
path: './loader', // Where to install loaders
type: null, // forge | neoforge | fabric | …
build: 'latest', // Build number / tag
enable: false, // Whether to install the loader
},

mcp: null, // Path to MCP config (legacy mods)

verify: false, // SHA‑1 check after download
ignored: [], // Files to skip verification
JVM_ARGS: [], // Extra JVM arguments
GAME_ARGS: [], // Extra game arguments

java: {
path: null, // Custom JVM path
version: null, // Explicit Java version
type: 'jre', // jre | jdk
},

screen: {
width: null,
height: null,
fullscreen: false,
},

memory: {
min: '1G',
max: '2G',
},
} as const;
`

> Note : Any field you provide when calling Launch.launch() will be
> merged on top of these defaults; you rarely need to specify more than
> authenticator, path, version and memory.

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#### Events

| Event Name | Payload | Description |
|-------------|---------|--------------------------------------------------------------|
| data | String | Raw output from the Java process. |
| progress | Number | Global download progress percentage. |
| speed | Number | Current download speed (kB/s). |
| estimated | Number | Estimated time remaining (s). |
| extract | String | Name of the file currently being extracted. |
| patch | String | Loader patch currently applied. |
| close | void | Emitted when the Java process exits. |
| error | Error | Something went wrong. |

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* Microsoft — OAuth 2 Device Code flow via Xbox Live → XSTS → Minecraft.
Mojang (legacy)* — classic Yggdrasil endpoint.
* AZauth — community Yggdrasil‑compatible server.

> The authenticator returns a profile object that you pass directly to Launch.launch().

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* Downloader — resilient downloader with resume, integrity check & progress/speed events.
* Status — simple TCP ping that returns MOTD, player count & latency.

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`
src/
Authenticator/ Microsoft, Mojang, AZauth flows
Minecraft/ Version JSON, assets, libraries, args builder
Minecraft-Loader/ Forge, NeoForge, Fabric, Quilt, … installers
StatusServer/ Server ping implementation
utils/ Downloader & helpers
Launch.ts Main entry point
assets/ LWJGL native indexes
``

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See the commit history for a full list. Special thanks to:

* Luuxis — original author.
* Community testers & issue reporters.

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Released under Creative Commons Attribution‑NonCommercial 4.0 International.