The Minecraft server JAR is the file that runs your own server. Downloading and launching it is simpler than many people think. This guide walks through getting the JAR, running it, and configuring it properly.
What the Server JAR Is
The server JAR is a Java program that hosts a Minecraft world for other players to join. There is an official vanilla JAR from Mojang, and there are community server software options like Paper and Spigot that add performance and plugin support.
Step 1: Install Java
The server JAR runs on Java, so you need a current Java runtime installed. Modern Minecraft versions require a recent Java version, so install the version that matches your Minecraft release. Without the right Java, the server will not start.
Step 2: Download the JAR
For a vanilla server, download the official server JAR for your version from the Minecraft site. For better performance and plugins, download a Paper JAR instead, which is a popular drop in replacement that runs much smoother for multiplayer.
Place the JAR in its own empty folder, since the server creates many files around it.
Step 3: Run the Server
Open a terminal in the folder and start the server with a command like this:
java -Xmx2G -Xms2G -jar server.jar nogui
The Xmx and Xms values set how much RAM the server uses, in this case 2 gigabytes. The nogui flag keeps it lightweight. Adjust the RAM to your machine and player count.
Step 4: Accept the EULA
The first launch stops and creates a file called eula.txt. Open it and change the line to:
eula=true
This accepts the Minecraft end user license agreement. Save the file and start the server again, and it will boot fully.
Step 5: Configure server.properties
After it starts, you get a server.properties file with all the main settings. Common ones to edit include:
- gamemode for survival or creative
- difficulty for the challenge level
- max-players for the slot count
- motd for the message shown in the server list
- online-mode, which should stay true for security in most cases
Edit, save, and restart for changes to apply.
Step 6: Let Players Connect
For friends to join over the internet, the server port must be reachable, which usually means port forwarding on a home connection, or simply using a hosting provider that gives you an open port. A dedicated host removes the port forwarding hassle and keeps the server online when your computer is off.
Vanilla vs Paper vs Modded
Vanilla is the pure experience with no plugins. Paper and Spigot add plugin support and big performance gains, which is what most multiplayer servers use. For mods, you use Forge or Fabric server software instead, matched to the modpack you want.
FAQ
Where do I download the Minecraft server JAR? The official vanilla JAR comes from the Minecraft site. For performance and plugins, use a Paper JAR.
Why does my server stop on first launch? It is waiting for you to accept the EULA. Set eula=true in eula.txt and restart.
How much RAM does a Minecraft server need? A small server runs on around 2 gigabytes, but more players and mods need more.
Related: How to reduce Minecraft server lag, Minecraft server requirements, Best Minecraft server plugins