Fabric 1.21.11-pre5_unobfuscated Server Jar Download

Official source

The Fabric server launcher for Minecraft 1.21.11-pre5_unobfuscated uses Fabric Loader 0.20.1 and installer 1.1.2; on first start it downloads the vanilla 1.21.11-pre5_unobfuscated server from Mojang.

Download

Download Fabric server launcher

Downloads from meta.fabricmc.net — Official — FabricMC.

The upstream does not publish a checksum for this file. MCJarHub computes a SHA-256 for such files on a schedule and shows it here once available — see how we source & verify.

Source: Official — FabricMC No checksum published yet Last checked: 28 Oct 2026, 12:46 UTC Report a problem

Version facts

Channel	Release
Fabric Loader	0.20.1
Fabric installer	1.1.2
Licence	Apache-2.0
Upstream project	fabricmc.net

What changed

Fabric Loader 0.20.1 release notes

Compatibility

Loads Fabric mods for Minecraft 1.21.11-pre5_unobfuscated.

Players need a Minecraft: Java Edition 1.21.11-pre5_unobfuscated client on the same version.

Known issues & safety notes

Back up your world before changing versions: worlds upgrade automatically on start and cannot be downgraded.
Known issues: search Fabric's issue tracker for 1.21.11-pre5_unobfuscated

How to set up Fabric 1.21.11-pre5_unobfuscated

Download the Fabric server launcher above (about 176 KB) into an empty folder.
Start it with the script below. On the first start the launcher downloads the vanilla 1.21.11-pre5_unobfuscated server from Mojang and the Fabric libraries — this needs internet access.
Accept Mojang's EULA in eula.txt (eula=true) and start again.
Put mods into mods/.

Linux / macOS — `start.sh`

#!/bin/sh
# start.sh — Fabric 1.21.11-pre5_unobfuscated
cd "$(dirname "$0")"
java -Xms6G -Xmx6G -jar fabric-server-mc.1.21.11-pre5_unobfuscated-loader.0.20.1-launcher.1.1.2.jar nogui

Windows — `start.bat`

@echo off
REM start.bat — Fabric 1.21.11-pre5_unobfuscated
java -Xms6G -Xmx6G -jar fabric-server-mc.1.21.11-pre5_unobfuscated-loader.0.20.1-launcher.1.1.2.jar nogui
pause

Modded servers need more memory: 6–8 GB for a light modpack, 8–12 GB or more for large packs. Leave 1–1.5 GB for the operating system. How much RAM?

Docker

docker run -d -p 25565:25565 -e EULA=TRUE -e TYPE=FABRIC -e VERSION=1.21.11-pre5_unobfuscated --name mc itzg/minecraft-server

Uses the community itzg/minecraft-server image, which downloads the file itself.

Upgrading

Newer: Fabric 1.21.11-rc1_unobfuscated
Previous: Fabric 1.21.11-pre4_unobfuscated
How to update a Minecraft server safely

FAQ

Why is the Fabric server file so small?

It is only a launcher. On the first start it downloads the vanilla Minecraft 1.21.11-pre5_unobfuscated server from Mojang and the Fabric Loader libraries.