Install a mod loader

You usually get a loader from a pack:

import modsmith as ms

game = ms.minecraft.GameDir.default()
pack = ms.packs.load("pack.mrpack")

version_id = pack.loader.install(game)

You can also install one directly. The version comes first, then the Minecraft version:

fabric = ms.loaders.Fabric("0.16.10", "1.21.1")
neoforge = ms.loaders.NeoForge("21.1.233", "1.21.1")
forge = ms.loaders.Forge("47.3.0", "1.20.1")
quilt = ms.loaders.Quilt("0.30.2", "1.21.1")

version_id = fabric.install(game)

install downloads Minecraft if needed, then the loader. It returns the version id to use in a launcher profile.

Build a loader from its name

This helps when a name comes from a file or a user:

loader = ms.loaders.create("fabric", "0.16.10", "1.21.1")
loader = ms.loaders.parse("forge-47.3.0", "1.20.1")

Check what is installed

if fabric.is_installed(game):
    print(fabric.expected_id())

is_installed reads local files, so it works offline. Installing a loader that is already there also returns straight away.

Choose a game directory

GameDir.default finds the official launcher’s folder. To install somewhere else, give it a path:

game = ms.minecraft.GameDir("my-launcher/minecraft")

Vanilla versions work the same way:

for version in ms.minecraft.list_versions()[:5]:
    print(version.id, version.type)

ms.minecraft.install_version(game, "1.21.1")

Forge and NeoForge take longer

Fabric and Quilt only download files. Forge and NeoForge also patch the game, which needs Java and can take a few minutes. Modsmith picks a Java runtime for you, and you can pass your own with java=:

from pathlib import Path

forge.install(game, java=Path("/usr/lib/jvm/java-21/bin/java"))

How loaders are installed explains why. Installers are cached, and you can move that cache with cache_dir=.

Supported versions

See Compatibility.