CurseForge · Minecraft mod
Cosmos Library
Main required library for the mods in The Cosmos Series.
Quick answer
Which Cosmos Library release should I use?
Cosmos Library cosmoslibrary-neoforge-1.21.1-11.11.9.0.jar targets 1.21.1 with NeoForge. The project page does not say whether it belongs on the client. The project page does not say whether it belongs on the dedicated server. No extra mods listed for this file.
Where it goes
Is Cosmos Library required on the client, server, or both?
The project page does not say whether it belongs on the client. The project page does not say whether it belongs on the dedicated server.
The source does not explicitly classify this release as client-only or server-only.
What else does Cosmos Library cosmoslibrary-neoforge-1.21.1-11.11.9.0.jar need?
cosmoslibrary-neoforge-1.21.1-11.11.9.0.jar. Change the file and its required mods may change too.
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 Cosmos Library without breaking your instance.
Built for Cosmos Library cosmoslibrary-neoforge-1.21.1-11.11.9.0.jar. Pick another file and the loader, install side or required mods may change.
- 01
Stick to this file
Use cosmoslibrary-neoforge-1.21.1-11.11.9.0.jar. It targets 1.21.1 with NeoForge; another release may have different loader, side or dependency requirements.
- 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.
- 03
Put it on the correct side
The project page does not say whether it belongs on the client. The project page does not say whether it belongs on the dedicated server.
- 04
Pick the file you checked
Use the “Get this file” button beside cosmoslibrary-neoforge-1.21.1-11.11.9.0.jar. It opens that exact file at the source.
About this project
What does Cosmos Library add?

Cosmos Library
Notices
Cosmos Library is now available for Minecraft 1.21.1 and NeoForge.
Description
Cosmos Library is a collection of helper functions to enable a quicker and more seamless creation of Minecraft Mods. It adds nothing to the game itself, it is simply a base upon which other mods are created. This also allows the reduction of common code distributed within other mods, as that common code is stored in this mod once.
This library is required for all mods in The Cosmos Series.
Developers
A note for any Developers looking to use Cosmos Library for their own projects:
Cosmos Library is made and used exclusively by TheCosmicNebula for The Cosmos Series. There is no official documentation, and there likely will never be. TheCosmicNebula will ruthlessly change or remove functions and classes with reckless abandon.
It is not recommended to use this library due to the high frequency of updates which will break compatibility. The source code is not kept up to date and updates are not broadcast outside of the changelog.
If you are still in need of a library to use, I would suggest looking for one with thorough documentation, and a discord server which announces changes. Or make your own.
The Cosmos Series
This mod is part of The Cosmos Series.
Project description from CurseForge.
Pick your setup
Cosmos Library by Minecraft version and loader
Choose the version and loader you play, then open the matching release.
1.21
1 loader build1.20.1
1 loader build1.19.2
1 loader build1.19.1
1 loader build1.18.2
1 loader build1.18.1
1 loader build1.17.1
1 loader buildCheck the dependencies, then try the file in a copied instance before changing a world you care about.
Recent files
Cosmos Library versions and loaders
cosmoslibrary-neoforge-1.21.1-11.11.9.0.jar
17 Mar 2026
cosmoslibrary-neoforge-1.21.1-11.11.8.0.jar
7 Feb 2026
cosmoslibrary-neoforge-1.21.1-11.11.7.0.jar
29 Jan 2026
cosmoslibrary-neoforge-1.21.1-11.11.6.0.jar
16 Jan 2026
cosmoslibrary-neoforge-1.21.1-11.11.5.0.jar
6 Aug 2025
cosmoslibrary-neoforge-1.21.1-11.11.4.0.jar
12 Apr 2025
cosmoslibrary-neoforge-1.21.1-11.11.0.0.jar
11 Apr 2025
cosmoslibrary-neoforge-1.21.1-11.10.0.0.jar
9 Apr 2025
cosmoslibrary-neoforge-1.21.1-11.9.10.0.jar
28 Mar 2025
cosmoslibrary-neoforge-1.21.1-11.9.0.0.jar
20 Mar 2025
cosmoslibrary-neoforge-1.21.1-11.8.0.0.jar
20 Mar 2025
cosmoslibrary-neoforge-1.21.1-11.7.0.0.jar
9 Mar 2025
Looking for an older file? The official CurseForge project page is in Resources.