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CurseForge · Minecraft mod

RainAPI

Core library for RainJava featuring embedded ECJ compiler, Javassist bytecode tools, and ASM transformation pipeline. Enables dynamic Java compilation and class modification at runtime.

Choose a version Pick your version below, then grab the matching file.

Quick answer

Which RainAPI release should I use?

Updated 6 months ago
Latest stable file RainAPI-1.0.0.jar
Game version 1.20.1
Loader Forge

RainAPI-1.0.0.jar targets 1.20.1 with Forge. The project page does not say whether this file belongs on the client, dedicated server, or both. No extra mods listed for this file.

Where it goes

Is RainAPI required on the client, server, or both?

The project page does not say whether this file belongs on the client, dedicated server, or both.

Client Source doesn’t say
Dedicated server Source doesn’t say
Loader for this release Forge
Required install it here Optional supported, not mandatory Not supported do not install here Source doesn’t say do not assume

The source does not explicitly classify this release as client-only or server-only.

What else does RainAPI-1.0.0.jar need?

RainAPI-1.0.0.jar. Change the file and its required mods may change too.

No extra mods listed for this file

This file does not list any required mods. Do not add a library just because a different file uses it.

This file does not list any required or optional mods.

Before you install it

Add RainAPI without breaking your instance.

Built for RainAPI-1.0.0.jar. Pick another file and the loader, install side or required mods may change.

  1. 01

    Stick to this file

    Use RainAPI-1.0.0.jar. It targets 1.20.1 with Forge; another release may have different loader, side or dependency requirements.

  2. 02

    Bring the mods it needs

    This file does not list any required mods. Do not add a library just because a different file uses it.

  3. 03

    Put it on the correct side

    The project page does not say whether this file belongs on the client, dedicated server, or both.

  4. 04

    Pick the file you checked

    Use the “Get this file” button beside RainAPI-1.0.0.jar. It opens that exact file at the source.

About this project

What does RainAPI add?

RainJava API

Advanced Runtime Class Transformation Framework

A foundational library providing Mixin and Coremod interoperability layers, powered by enterprise-grade bytecode and compilation tools.

Overview

RainJava API establishes the critical infrastructure for runtime class transformation pipelines. It serves as a middleware bridge between dynamic compilation workflows and Minecraft's standard modification systems (Mixin & Coremod), ensuring bytecode-level compatibility without compromising game stability.

While designed as the prerequisite foundation for the upcoming RainJava ecosystem, this API functions independently as a robust toolkit for developers requiring deep class manipulation capabilities.

Embedded Libraries

This mod ships with zero-external-dependency versions of industry-standard tools:

  • Javassist — High-level bytecode manipulation library for runtime class engineering

  • ECJ (Eclipse Compiler for Java) — Full-featured Java compiler capable of runtime source-to-bytecode transformation

  • JavaParser — Abstract Syntax Tree (AST) analysis and code generation framework

These libraries are shaded and isolated to prevent conflicts with other mods.

Technical Scope

  • Transformation Bridge — Facilitates communication between runtime-generated class definitions and established bytecode modification frameworks

  • Mixin Compatibility Layer — Enables standardized injection patterns to recognize and process dynamically provisioned classes

  • Coremod Integration — Provides stable hooks for runtime class definitions to participate in Forge's transformation chain

  • Sandboxed Execution — Implements security boundaries for runtime code evaluation environments

For Modders

Install this API if you:

  • Plan to develop for or use the upcoming RainJava framework

  • Require embedded Javassist/ECJ/JavaParser without bundling them yourself

  • Need stable Mixin/Coremod interoperability for advanced bytecode operations

Project description from CurseForge.

Pick your setup

RainAPI by Minecraft version and loader

Choose the version and loader you play, then open the matching release.

1 available setups

Check the dependencies, then try the file in a copied instance before changing a world you care about.

Recent files

RainAPI versions and loaders

1 of 1 releases match

Looking for an older file? The official CurseForge project page is in Resources.