Minecraft Multiloader

Minecraft Multiloader Skill (Architectury)

What Is Architectury?

Architectury is a framework that lets you write one mod codebase that compiles to both NeoForge and Fabric JARs. The common subproject has a shared API; platform subprojects implement platform-specific behavior behind the @ExpectPlatform abstraction.

Routing Boundaries

• Use when: one shared codebase must build and ship both NeoForge and Fabric artifacts.
• Do not use when: the project is single-loader only (minecraft-modding for NeoForge/Fabric, not both).
• Do not use when: the task is Paper/Bukkit plugin development (minecraft-plugin-dev).

Versions (Retained 1.21.11 Lane)

# gradle.properties property names used by this skill's static helper.
# Get every tool version from the exact generated or known-working project.
mod_version=1.0.0
minecraft_version=1.21.11
enabled_platforms=fabric,neoforge

architectury_version=<project pin>
fabric_loader_version=<project pin>
fabric_api_version=<project pin ending in +1.21.11>
neoforge_version=<project pin in the 21.11.x family>
loom_version=<project pin>

Pin architectury_version, the Architectury plugin version, and loom_version from the same generated or known-working project line. This skill deliberately does not publish a copyable dependency matrix: its static helper cannot resolve whether a particular set of versions is compatible.

For the current Minecraft 26.2 / Java 25 lane, use the official Architectury Template Generator only when its version selector offers the exact target. Generate a Multiplatform project with Fabric and NeoForge, then preserve the generated Gradle layout and pins as one set. If the generator does not offer the target, begin with an already working project on that exact line and inspect its resolved build; do not relabel a 1.21.11 template as 26.2. The published template downloads are not a substitute for an exact-current scaffold.

Do not mechanically change only minecraft_version in the retained example: 26.2 is unobfuscated and its Loom/remapping setup differs from 1.21.11.

Bundled References And Helpers

• Version alignment reference: references/architectury-reference.md
• Sanity checker: ./scripts/check-version-sanity.sh --root <project>

Run the sanity checker after editing gradle.properties. It is a static syntax-and-version-family preflight: it catches missing keys, snapshot pins, missing fabric / neoforge platforms, and obvious version-family drift. It does not resolve dependencies, prove loader compatibility, or replace the project's Fabric and NeoForge build and smoke tests.

Root Project Layout

my-mod/
├── build.gradle           ← root build (shared config)
├── settings.gradle
├── gradle.properties
├── common/
│   ├── build.gradle
│   └── src/main/java/com/example/mymod/
│       ├── MyMod.java               ← shared init
│       ├── registry/
│       │   └── ModItems.java        ← shared registry declarations
│       └── platform/
│           └── PlatformHelper.java  ← @ExpectPlatform methods
├── fabric/
│   ├── build.gradle
│   └── src/main/
│       ├── java/com/example/mymod/fabric/
│       │   ├── MyModFabric.java          ← Fabric entrypoint
│       ├── java/com/example/mymod/platform/
│       │   └── PlatformHelperImpl.java   ← Fabric @ExpectPlatform implementation
│       └── resources/
│           ├── fabric.mod.json
│           └── assets/...
└── neoforge/
    ├── build.gradle
    └── src/main/
        ├── java/com/example/mymod/neoforge/
        │   ├── MyModNeoForge.java        ← NeoForge @Mod entry
        ├── java/com/example/mymod/platform/
        │   └── PlatformHelperImpl.java   ← NeoForge @ExpectPlatform implementation
        └── resources/
            ├── META-INF/neoforge.mods.toml
            └── assets/...

Legacy Build Template

The old fixed Gradle scripts were a 1.21.11 snapshot and are intentionally not presented as a current scaffold. For either supported lane, read references/legacy-1.21.11-template.md or references/architectury-reference.md before changing generated build files. They preserve version anchors and source-set boundaries without encouraging a partial build script to be copied into a different Minecraft line.

Shared Common Code

common/.../MyMod.java

package com.example.mymod;

import dev.architectury.registry.registries.DeferredRegister;
import dev.architectury.registry.registries.RegistrySupplier;
import net.minecraft.core.registries.Registries;
import net.minecraft.resources.Identifier;
import net.minecraft.resources.ResourceKey;
import net.minecraft.world.item.Item;

public class MyMod {
    public static final String MOD_ID = "mymod";

    // Architectury's DeferredRegister — works on both platforms
    public static final DeferredRegister<Item> ITEMS =
        DeferredRegister.create(MOD_ID, Registries.ITEM);

    public static final RegistrySupplier<Item> MY_ITEM =
        ITEMS.register("my_item", () -> new Item(new Item.Properties().setId(
            ResourceKey.create(Registries.ITEM,
                Identifier.fromNamespaceAndPath(MOD_ID, "my_item"))
        )));

    public static void init() {
        ITEMS.register(); // registers with both platforms
    }
}

@ExpectPlatform — platform-specific methods

Define the contract in common/:

package com.example.mymod.platform;

import dev.architectury.injectables.annotations.ExpectPlatform;
import net.minecraft.world.level.material.Fluid;

public class PlatformHelper {

    @ExpectPlatform
    public static boolean isModLoaded(String modId) {
        // This body is replaced at compile time by the platform implementation
        throw new AssertionError("ExpectPlatform implementation not found");
    }

    @ExpectPlatform
    public static boolean isClient() {
        throw new AssertionError();
    }
}

Keep each platform implementation in the same Java package as the common @ExpectPlatform class. Only the source set changes between common/, fabric/, and neoforge/.

Implement in fabric/.../platform/PlatformHelperImpl.java:

package com.example.mymod.platform;

import net.fabricmc.loader.api.FabricLoader;

// Class name must match: <common class name>Impl
public class PlatformHelperImpl {

    public static boolean isModLoaded(String modId) {
        return FabricLoader.getInstance().isModLoaded(modId);
    }

    public static boolean isClient() {
        return FabricLoader.getInstance().getEnvironmentType() ==
            net.fabricmc.api.EnvType.CLIENT;
    }
}

Implement in neoforge/.../platform/PlatformHelperImpl.java:

package com.example.mymod.platform;

import net.neoforged.fml.ModList;
import net.neoforged.fml.loading.FMLEnvironment;

public class PlatformHelperImpl {

    public static boolean isModLoaded(String modId) {
        return ModList.get().isLoaded(modId);
    }

    public static boolean isClient() {
        return FMLEnvironment.dist.isClient();
    }
}

Fabric Entrypoint

fabric/.../MyModFabric.java

package com.example.mymod.fabric;

import com.example.mymod.MyMod;
import net.fabricmc.api.ModInitializer;

public class MyModFabric implements ModInitializer {
    @Override
    public void onInitialize() {
        MyMod.init();
    }
}

fabric/.../resources/fabric.mod.json

This retained-1.21.11 metadata example follows the minimum dependencies in the upstream Architectury 1.21.11 branch. Keep the generated project's exact ranges when they are stricter.

{
  "schemaVersion": 1,
  "id": "mymod",
  "version": "${version}",
  "name": "My Mod",
  "description": "A multiloader example mod",
  "license": "MIT",
  "environment": "*",
  "entrypoints": {
    "main": ["com.example.mymod.fabric.MyModFabric"]
  },
  "depends": {
    "fabricloader": ">=0.18.2",
    "fabric-api": ">=0.139.4+1.21.11",
    "architectury": ">=19.0",
    "minecraft": "~1.21.11"
  }
}

NeoForge Entrypoint

neoforge/.../MyModNeoForge.java

package com.example.mymod.neoforge;

import com.example.mymod.MyMod;
import net.neoforged.bus.api.IEventBus;
import net.neoforged.fml.common.Mod;

@Mod(MyMod.MOD_ID)
public class MyModNeoForge {
    public MyModNeoForge(IEventBus modEventBus) {
        MyMod.init();
    }
}

neoforge/.../resources/META-INF/neoforge.mods.toml

modLoader = "javafml"
loaderVersion = "[1,)"
license = "MIT"

[[mods]]
modId = "mymod"
version = "${file.jarVersion}"
displayName = "My Mod"
description = "A multiloader example mod"

[[dependencies.mymod]]
modId = "neoforge"
type = "required"
versionRange = "[21.11,)"
ordering = "NONE"
side = "BOTH"

[[dependencies.mymod]]
modId = "minecraft"
type = "required"
versionRange = "[1.21.11,1.22)"
ordering = "NONE"
side = "BOTH"

Build Commands

# Build both JARs simultaneously
./gradlew build

# Inspect the project's actual outputs. Generated templates choose their own
# archive base name and version convention:
find fabric/build/libs neoforge/build/libs -maxdepth 1 -type f -name '*.jar' \
  ! -name '*-sources.jar' ! -name '*-dev.jar' ! -name '*-javadoc.jar'

# Run in dev environment
./gradlew :fabric:runClient
./gradlew :neoforge:runClient
./gradlew :neoforge:runServer

# Datagen (if applicable)
./gradlew :neoforge:runData

Common Pitfalls

References

• Architectury API GitHub: https://github.com/architectury/architectury-api
• Architectury API 26.2 source branch: https://github.com/architectury/architectury-api/tree/26.2
• Architectury API 1.21.11 source branch: https://github.com/architectury/architectury-api/tree/1.21.11
• Architectury Loom: https://github.com/architectury/architectury-loom
• Architectury templates: https://github.com/architectury/architectury-templates
• Architectury Template Generator: https://generate.architectury.dev/
• Architectury docs: https://docs.architectury.dev/