Status
January 23rd, 2022
This repository has been archived as we do not have the time or resources needed to maintain the project. No further updates will be published, and we won't be providing help for using it.
If you are looking for a replacement, consider taking a look at FerriteCore, as it generally offers more significant improvements to memory usage in modded scenarios and is currently available for the latest version of Minecraft.

Memory usage before and after installing Hydrogen into the popular All of Fabric 3 modpack.
Hydrogen is a free and open-source mod designed to reduce the game's memory requirements by implementing more memory-efficient data structures and logic. It's primarily designed for more heavily modded scenarios, but can offer (small) improvements even in lightly modded or vanilla scenarios.
The mod works on both the client and server, and doesn't require the mod to be installed on both sides. However, the benefits of running Hydrogen on the server are pretty small as of the moment.
Features
Implements more compact data structures for block states and properties, reducing memory usage significantly when using mods that add lots of complex blocks
De-duplicates block model geometry, saving memory on the client when multi-part block models are used
Fixes a few leaks in chunk loading code that results in the NBT data on disk being kept in memory after a chunk has loaded
Simplifies and flattens block model predicates to reduce unnecessary chaining
- Edition: Minecraft Java
- File type: .jar
- Minecraft versions listed: 1.17, 1.17.1
- How to install: Install the matching mod loader (Forge, Fabric or NeoForge) for your Minecraft version. → Download the .jar. → Put it in the .minecraft/mods folder and launch that loader profile.
- Where to get it: Opens on Modrinth — not every file is mirrored on our own servers.
Install steps are the general flow for this file type — How to install Minecraft Java mods & modpacks walks through it step by step.
- Ships as hydrogen-fabric-mc1.17.1-0.3.jar — drop this file into the mods folder
- Download size: 116 KB
- Download link checked 26 Aug 2026 — working
These come from our own check of the pack file, not from the source page.
