Koremods
by Su5eD
Koremods is a Forge library that lets other mods run Kotlin scripts which rewrite Java bytecode at load time, with the scripts compiled during play.
What it does
Scripts are run in an isolated environment, so they reach only the classes and resources they need. Using the ASM Kotlin wrapper Koffee, a script author can focus on writing transformers instead of repeating low-level setup. The core is kept lightweight, and it is designed around a thin frontend layer, so a platform frontend only has to connect the platform to Koremods Script. The Modlauncher frontend for Forge is published as the releases of this project.
Kotlin scripting is an experimental technology that allows Kotlin code to run without prior compilation or packaging. Each script gets turned into JVM instructions while the game runs, then a custom classloader brings it into memory, and every Kotlin language feature is available, usually together with a DSL supplied by the script definition. Koremods is published for Forge only, across five release versions: 1.18.2, 1.19.2, 1.19.3, 1.20.1 and 1.20.4, with 2.0.0 for 1.20.4 as the latest file. The mod is released under the MIT License and is open source.
Koremods is required by Somnia Awoken, so that mod needs it installed alongside. Every player and the server need a copy of the mod.
Key features
Sandboxed script execution
Scripts run in an isolated environment that limits them to the classes and resources they actually need.
Koffee transformer wrapper
The ASM Kotlin wrapper Koffee removes repetitive boilerplate from writing bytecode transformers.
Lightweight runtime
The core stays small, so script loading adds little overhead to the game.
Thin frontend layer
Each platform needs only a thin layer between itself and Koremods Script, which keeps the core reusable.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Required by 1 mod
Use cases
Modpack authors
Authors who need a change to vanilla or modded classes can write a short Kotlin script instead of a full mod.
Mod developers
Developers who ship a Forge mod that depends on bytecode transformation can build on the library rather than writing their own loader.
Who it’s for: Mod developers and modpack authors who want to write Kotlin bytecode transformers for Forge, and server owners who run mods that require Koremods.
How it compares
Kotlin Script For Forge is a server-side required mod, with the server needing it while clients may leave it out. It is open source under the MIT License and has files for 1.18 – 1.19.2 on Forge. RainAPI is a client and server mod for 1.20.1 under the MIT License, and it is not open source. Koremods covers the newer 1.18.2 – 1.20.4 range and is a library for scripting bytecode rather than a general API.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Koremods | Forge | 1.18.2 – 1.20.4 | Client and server | 2023-12-27 |
| Kotlin Script For Forge | Forge | 1.18 – 1.19.2 | Server required, client optional | 2024-05-01 |
| RainAPI | Forge | 1.20.1 | Client and server | 2026-02-27 |
Questions
Does Somnia Awoken need Koremods?
Does Koremods have to be installed on both sides?
Which Minecraft versions does Koremods support?
In the catalog
Koremods is one of 3,514 Library mods on ModsFinder, and one of 1,576 Library mods for Forge. 13,907 mods support Minecraft 1.20.4.
More from Su5eD
Similar mods
What the author says
Koremods is a Kotlin Script bytecode manipulation framework. It providers modders a new way of transforming (not just) minecraft bytecode with rich IDE support and Gradle integration. This Modrinth project contains releases for Koremods Modlauncher, the MinecraftForge frontend.
Official listing
- Modrinth page
- modrinth.com/mod/koremods
- Owner
- Su5eD
- Published
- 2022-06-09
- Updated on Modrinth
- 2023-12-27
- Facts verified
- 2026-10-15