How to Install Fabric Language Kotlin as a Dependency for Another Mod

Fabric Language Kotlin is a library, not a content mod. You will almost never install it because you want it for itself — you install it because another mod you downloaded refuses to launch without it. If a mod crashes on startup with a message about missing Kotlin classes or a missing fabric-language-kotlin dependency, this is the fix.

Confirm the Mod Actually Needs It

Open your mods folder and check the mod that failed. Most mod pages list their required dependencies, and Kotlin-based mods will name Fabric Language Kotlin explicitly. If the crash log mentions kotlin anywhere in the stack trace, that is your confirmation.

Place It Alongside the Dependent Mod

Drop the Fabric Language Kotlin jar into the same mods folder as the mod that needs it. Both jars must be present at the same time — removing either one breaks the other. Do not rename the jar file; Fabric's loader reads metadata from the file itself.

Verify It Loaded

Launch the game and open the mod list. Fabric Language Kotlin should appear as an entry even though it adds no items or blocks. If the dependent mod now loads without a crash, the dependency is satisfied. If you still see a Kotlin-related error, the dependent mod likely targets a different loader version, and you should match the two mods to the same Minecraft version.