Kotlin for Forge

Kotlin for Forge is a library mod that adds a Kotlin language loader for Forge and NeoForge, letting mod developers write Minecraft mods in Kotlin instead of Java. It ships the Kotlin standard library, reflection, coroutines, and JSON serialization already shaded in, so mods that depend on it need no separate Kotlin runtime install. If you are not a mod developer, this is a dependency: install it because something else on your list requires it, not because you will interact with it directly.

What Kotlin for Forge adds

The mod provides a KotlinLanguageProvider so Kotlin object declarations can load as @Mod entry points, and an AutoKotlinEventBusSubscriber so Kotlin objects can register as Forge event listeners without extra Java glue code. It also bundles utility functions Kotlin developers reach for constantly, alongside the Kotlin coroutines and JSON serialization libraries, so a mod can lean on Kotlin's language features without asking every downstream user to solve dependency versions on their own.

Forge and NeoForge version support

Kotlin for Forge ships separate build artifacts for each loader, and the two are not on the same version track. The Forge build tops out at Minecraft 1.21.11, last released in October 2025. The NeoForge build is meaningfully ahead, current through Minecraft 26.2 as of a June 2026 release. A project targeting the newest Minecraft drops needs NeoForge; Forge users are capped at 1.21.11 until a newer build ships.

Installing it as a dependency

Kotlin for Forge is not something most players seek out on its own. It shows up as a required dependency when a Forge or NeoForge mod is built with Kotlin, and that mod's own page will say so. Download the build matching your loader from the project's Modrinth page and drop the jar in the mods folder alongside the mod that needs it, the same way Fabric API sits next to Fabric mods. If Forge or NeoForge is not installed yet, set one of those loaders up first, since Kotlin for Forge only runs on top of one of them. Fabric modders reach for Fabric Language Kotlin instead, since this project only targets Forge and NeoForge.

Adding it to a mod project

• Add the project's Maven repository, thedarkcolour.github.io/KotlinForForge, to build.gradle.
• Depend on kotlinforforge for Forge or kotlinforforge-neoforge for NeoForge, matching whichever loader the mod targets.
• Set modLoader to kotlinforforge in mods.toml (or neoforge.mods.toml) to load Kotlin object declarations as @Mod entry points.
• Skip the language loader entirely and just use it for the bundled Kotlin, coroutines, and serialization libraries, if that is all a project needs.