JFFL

Mod

JFFL is a tool used to Javassist of Minecraftforge bytecode operation library, provides mixin-like declarative patch injection it allows developers to use annotations at startup to modify the Minecraft and other mod classes.

Type

Mod

Modrinth Downloads

Modrinth ID

lTm9zXaK

Last Updated

May 14, 2026

Description

JFFL - Javassist Framework for Forge Loader

JFFL is a bytecode manipulation library for Minecraft Forge based on Javassist, providing Mixin-like declarative patch injection capabilities. It allows developers to modify classes from Minecraft and other mods at runtime using annotations, without the need to write low-level ASM or Javassist code directly.

Features

Declarative Annotation-Driven
Callback Handlers
Mapping Remapping Support
Flexible Injection Points

Installation and Dependencies

repositories { // Put the .jar of JFFL mod into the libs folder flatDir { dir 'libs' } } // Write in dependencies (replace {versino} with the actual version number): dependencies { implementation fg.deobf("wertygh:jffl:{version}") }

Relationship with Mixin

JFFL is not a replacement for Mixin but rather provides an alternative option. Both can coexist, though applying both to the same class is not recommended as it may lead to unexpected conflicts. JFFL's advantages include: