Collisions Lib
Minecraft mobs have always been a little ghostly. You can push a cow, sure, but try standing on one and you will fall straight through it. Collisions Lib changes that in one small but surprisingly fun package. This lightweight library mod gives every mob a solid hitbox, so creatures behave more like boats and shulkers than the intangible wanderers you are used to.
If you have ever wanted to build a pig tower, park a ravager in a doorway, or simply stop mobs from phasing through each other in a crowded farm, this is the add-on that makes it happen. It is a library at heart, which means other mods can hook into it, but it also works perfectly well on its own for players who just want a more physical world.
What Collisions Lib Actually Does
At its core, the mod replaces the default soft collision behavior of mobs with a proper solid hitbox. In vanilla Minecraft, most entities use a collision system that lets players and other mobs pass through them with only a gentle nudge. Boats and shulkers are the famous exceptions, and that is exactly the behavior Collisions Lib extends to the rest of the mob roster.
The result is immediate and very noticeable. You can stand on a zombie without sinking. Chickens can pile up and stay piled up. Mobs no longer clip through one another when they bunch together at a spawner or a breeding pen. It sounds like a tiny change, and technically it is, but it reshapes how the game feels in motion.
Key features at a glance
- Solid hitboxes for all mobs, matching the behavior of boats and shulkers.
- A configurable flag that can be disabled to make mobs intangible again.
- Lightweight library design so other mods can depend on it.
- Requires Fabric API and runs on the Fabric loader.
Supported Versions and Loader
Collisions Lib is built for the Fabric mod loader and depends on Fabric API to function. It targets modern Minecraft releases, and the exact supported Minecraft versions are listed on the project page, so check there before you download Collisions Lib to make sure your game build matches. Because it is a library, many packs and add-ons bundle it as a dependency, which means you may already have it installed without realizing it.
If you are running a server, the mod needs to be present on both the client and the server for the solid hitbox behavior to sync properly. Mixing versions across client and server is the most common cause of odd collision glitches, so keep them aligned.
For players who would rather skip the manual file shuffling, the foxygame.net launcher handles the whole process in a single click, and it keeps Collisions Lib updated automatically whenever a new build drops for your selected Minecraft version.
How to Install Collisions Lib
Getting the mod running is a short process, even if you have never touched a mod folder before. Here is how to install it step by step.
Step-by-step setup
- Install the Fabric loader for your Minecraft version if you have not already.
- Download Fabric API and place it in your mods folder.
- Download Collisions Lib and drop the jar file into the same mods folder.
- Launch the game using the Fabric profile and confirm the mod loads.
On Windows, the mods folder usually lives at .minecraft/mods. On macOS and Linux you will find it inside your user directory under the same name. If the folder does not exist, simply create it. Once both jars are in place, start the game and check the mod list on the title screen.
Configuring the flag
The mod ships with a flag that controls whether mobs stay solid. If you decide you prefer the original vanilla feel, you can disable it and mobs become intangible again without uninstalling anything. This makes Collisions Lib safe to keep around even when you are not actively using its main feature, and it is a big reason server owners leave it installed permanently.
Why Players Keep It Installed
Collisions Lib for Minecraft is one of those quiet quality-of-life additions. It does not add new blocks, mobs, or dimensions. It just fixes an inconsistency that has existed since the early days of the game. Builders use it to create mob-based platforms and traps. Redstone engineers use it to control how entities stack in confined spaces. Modpack authors use it as a dependency so their own creatures behave consistently with boats and shulkers.
The performance cost is negligible. Because it is a library, the code is lean and designed to be shared rather than duplicated across a dozen separate mods. That keeps your load times and memory usage in check, which matters once you are running a hundred other add-ons.
If you want a more physical, more predictable Minecraft where mobs actually occupy space, Collisions Lib delivers exactly that with almost no setup and no downside. Grab Fabric API, install the mod, and watch your next cow tower stand up on its own.
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