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Essential supports multiple mod loader platforms, each with different loading mechanisms and requirements. This page explains how Essential adapts to different platforms.

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Platform types

Essential categorizes mod loaders into four platform variants based on their loading mechanism:
PlatformLoaderMinecraft VersionsDescription
launchwrapperForge1.8.9, 1.12.2Legacy Forge using LaunchWrapper
modlauncher8Forge1.16.5Modern Forge with ModLauncher 8
modlauncher9Forge/NeoForge1.17+Modern Forge/NeoForge with ModLauncher 9+
fabricFabricAll Fabric versionsFabric loader
These platform variants determine which container mod and loader stages are used. Each platform has its own set of loader JAR files.

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Forge platforms

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LaunchWrapper (legacy)

Platform identifier: launchwrapper Minecraft versions: 1.8.9, 1.12.2 Legacy Forge versions use the LaunchWrapper system for mod loading:
  • Tweaker-based loading mechanism
  • FML (Forge Mod Loader) integration
  • Development uses custom DevelopmentTweaker for Mixin support
  • Most stable and mature Essential implementation

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ModLauncher 8

Platform identifier: modlauncher8 Minecraft versions: 1.16.5 Forge 1.16.5 introduced ModLauncher 8:
  • Service-based loading architecture
  • Improved transformation system
  • Transition version between legacy and modern Forge

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ModLauncher 9+

Platform identifier: modlauncher9 Minecraft versions: 1.17.1 and above Modern Forge and all NeoForge versions use ModLauncher 9 or newer:
  • Latest Forge loading architecture
  • Used by NeoForge since its inception (1.20.4+)
  • Unified platform for Forge 1.17+ and all NeoForge versions
  • Enhanced security and validation features

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Fabric platform

Platform identifier: fabric Minecraft versions: All Fabric-supported versions (1.16.2+) Fabric uses a different loading approach than Forge:
  • Lightweight loader with minimal modifications to Minecraft
  • Mixin-based transformation system
  • Requires fabric.mod.json for mod metadata
  • Separate loader versioning (Essential requires Fabric Loader 0.11.0+)
Essential compiles against Fabric Loader 0.11.0 to ensure compatibility with older versions while avoiding APIs only available in newer loaders.

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Fabric API integration

For Minecraft 1.20.6 and above, Essential bundles specific Fabric API modules:
  • fabric-api-base
  • fabric-networking-api-v1
These are included directly in the mod JAR to ensure necessary APIs are available.

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NeoForge platform

Platform identifier: modlauncher9 (shares infrastructure with modern Forge) Minecraft versions: 1.20.4 and above NeoForge is a fork of Forge that maintains compatibility with the ModLauncher 9 infrastructure:
  • Uses same platform variant as Forge 1.17+
  • Separate mod metadata format (neoforge.mods.toml)
  • Full feature parity with Forge builds
  • Growing support for modern Minecraft versions

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Container mods

Essential distributes lightweight “container” mods that download the full mod on first launch. There are four container variants, one for each platform:
ContainerPlatformUsed For
container-launchwrapperlaunchwrapperForge 1.8.9, 1.12.2
container-modlauncher8modlauncher8Forge 1.16.5
container-modlauncher9modlauncher9Forge 1.17+, NeoForge
container-fabricfabricAll Fabric versions

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Building container mods

To build a container mod for a specific platform: 
./gradlew :loader:container:<platform>:build
Examples: 
./gradlew :loader:container:fabric:build
./gradlew :loader:container:launchwrapper:build
./gradlew :loader:container:modlauncher9:build
Container JARs are output to loader/container/<platform>/build/libs/.

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Loader stages

Each platform has three loader stages with separate JAR files:

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Stage 0

Bootstraps Essential loading from the mod file:
  • Extracted from container or pinned mod JAR
  • Platform-specific initialization code
  • Minimal dependencies

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Stage 1

Sets up the loading environment:
  • Located at .minecraft/essential/loader/stage1.jar
  • Shared across all versions using the same platform
  • Loads Stage 2

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Stage 2

Prepares for mod execution:
  • Located at .minecraft/essential/loader/stage2.<Loader>_<MC-Version>.jar
  • Platform and version-specific
  • Loads the main Essential mod JAR
  • May be updated independently of Essential versions
For detailed technical information about loader stages, see loader/docs/stages.md in the source repository.

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Platform detection in code

The build system provides platform detection properties: 
val mcPlatform: String // "forge", "fabric", or "neoforge"

// Platform check helpers
platform.isFabric      // true for Fabric
platform.isForge       // true for Forge (not NeoForge)
platform.isNeoForge    // true for NeoForge
platform.isLegacyForge // true for LaunchWrapper versions

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Platform-specific configuration

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Mixin configurations

Fabric and Forge use different Mixin configuration approaches: Forge/NeoForge: Mixins declared in JAR manifest 
MixinConfigs: mixins.essential.json,mixins.essential.init.json,...
Fabric: Mixins declared in fabric.mod.json 
{
  "mixins": [
    "mixins.essential.json",
    "mixins.essential.init.json"
  ]
}

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Metadata formats

Each platform uses different mod metadata:
  • Forge (legacy): mcmod.info
  • Forge (modern): mods.toml
  • NeoForge: neoforge.mods.toml (becomes mods.toml in JAR)
  • Fabric: fabric.mod.json

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Building loader components

To build all loader components for all platforms: 
./gradlew build
Loader JARs are output to:
  • loader/stage0/<platform>/build/libs/
  • loader/stage1/<platform>/build/libs/
  • loader/stage2/<platform>/build/libs/
  • loader/container/<platform>/build/libs/
The loader is built automatically when building Essential mod since it’s included in the pinned JAR files.

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