Minecraft Server Startup Script Generator

Make a start.bat or start.sh for your server with the right memory settings and Aikar's flags, the Java settings PaperMC recommends for smoother performance.

RAM for the server (GB)4 GBNot sure? Use the RAM calculator.Server jar file nameFor example paper-1.21.4-232.jar. It has to match the file next to the script.

Computer

Java flags

Restart automatically if it stops or crashes Show the server's window (GUI)

start.bat

@echo off
:start
java -Xms4G -Xmx4G -XX:+UseG1GC -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:+AlwaysPreTouch -XX:G1NewSizePercent=30 -XX:G1MaxNewSizePercent=40 -XX:G1HeapRegionSize=8M -XX:G1ReservePercent=20 -XX:G1HeapWastePercent=5 -XX:G1MixedGCCountTarget=4 -XX:InitiatingHeapOccupancyPercent=15 -XX:G1MixedGCLiveThresholdPercent=90 -XX:G1RSetUpdatingPauseTimePercent=5 -XX:SurvivorRatio=32 -XX:+PerfDisableSharedMem -XX:MaxTenuringThreshold=1 -Dusing.aikars.flags=https://mcflags.emc.gs -Daikars.new.flags=true -jar server.jar --nogui
echo Server stopped. Restarting in 10 seconds - press Ctrl+C to cancel.
timeout /t 10
goto start

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Which Java do I need?

Minecraft 26.1 and newer	A recent Java - check that version's release notes
Minecraft 1.20.5 to 1.21.x	Java 21
Minecraft 1.18 to 1.20.4	Java 17
Minecraft 1.17	Java 16
Minecraft 1.16.5 and older	Java 8

If the server closes straight away with "UnsupportedClassVersionError", your Java is too old for that Minecraft version. Setting the minimum and maximum memory (-Xms and -Xmx) to the same value is intentional: Java grabs the memory once at start instead of resizing while players are online.