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This repository has been archived by the owner on Jan 24, 2022. It is now read-only.


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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This repository has been archived as we do not have the time or resources needed to maintain the project.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.

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Hydrogen (for Fabric)

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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.

Why are these patches not in Lithium?

Hydrogen relies on rather egregious hacks in order to load some code into the game, primarily because the Guava library developers really do not want people re-implementing their interfaces. These hacks are "safe" in the sense that the game will simply fail to start if a problem occurs, but are really rather not suitable for the standards which Lithium intends to promote. In other words, this mod could be looked at as "things too dirty to put in Lithium."

Installation instructions

Hydrogen relies on the Fabric Loader. Users should select Fabric for either the Minecraft launcher (client) or the dedicated server (server) depending on their needs. Once you have installed Fabric, place the Hydrogen .jar in the mods folder generated by Fabric.


If you'd like to get help with the mod, check out the latest developments, or be notified when there's a new release, the Discord community might be for you! You can join the official server for my mods by clicking here.

Building from source

If you're hacking on the code or would like to compile a custom build of Hydrogen from the latest sources, you'll want to start here.


You will need to install JDK 8 in order to build Hydrogen. You can either install this through a package manager such as Chocolatey on Windows or SDKMAN! on other platforms. If you'd prefer to not use a package manager, you can always grab the installers or packages directly from AdoptOpenJDK.

On Windows, the Oracle JDK/JRE builds should be avoided where possible due to their poor quality. Always prefer using the open-source builds from AdoptOpenJDK when possible.


Navigate to the directory you've cloned this repository and launch a build with Gradle using gradlew build (Windows) or ./gradlew build (macOS/Linux). If you are not using the Gradle wrapper, simply replace gradlew with gradle or the path to it.

The initial setup may take a few minutes. After Gradle has finished building everything, you can find the resulting artifacts in build/libs.


Hydrogen is licensed under GNU LGPLv3, a free and open-source license. For more information, please see the license file.