How to Make a Modded Minecraft Server on Your PC

A modded server is the normal Minecraft server with a mod loader underneath and the pack's mods on top. This guide covers the free route on your own PC first, then the same setup on a CraftLands server that stays online when your PC is off.

What every modded server needs

Three things must match between the server and every player, or players are disconnected at login:

• The Minecraft version. A 1.20.1 pack needs a 1.20.1 server, not a newer one.
• The mod loader. Forge, NeoForge and Fabric are separate loaders, so a Forge pack needs a Forge server. Use the loader version the pack lists.
• The mod list. Every mod that adds blocks, items or mobs goes on both sides at the same version. Client-only mods such as Sodium stay on the players' side.

The Minecraft version also decides which Java the server needs. These are the Java versions Mojang lists for each release in its version manifest, checked on 30 September 2026:

Install that version on the PC that runs the server, for example the free Temurin builds from Adoptium, then check it with the command below. If a pack's own page names a different Java version, follow the pack.

java -version

Forge, NeoForge or Fabric

The pack decides the loader. What changes between them is where the server comes from and how you start it:

How to make a modded Minecraft server on your PC

Running the server on your own PC is free. The world is online only while that PC is on, and the server needs its own RAM on top of the game if you play on the same machine.

Option 1: start from the pack's server files

A CurseForge pack can come with a server pack: the same pack, prepared by its author to run on a server. When your pack has one, this is the shortest route.

1. 1Open the pack's page on CurseForge and go to the Files tab.
2. 2Find the file with the same version your players installed, and download the server pack attached to it as an additional file.
3. 3Unzip it into an empty folder.
4. 4Start it with the script the pack includes, following its README if there is one.
5. 5The first launch stops on purpose. Open eula.txt, change eula=false to eula=true, save it and start the server again.
6. 6Once it has finished loading, join from your own game through Multiplayer with the address localhost.

Option 2: build it from the loader installer

Use this when the pack has no server files, or when you put the pack together yourself in the CurseForge app.

1. 1Note the pack's Minecraft version and exact loader version.
2. 2Download that loader version from its official site and install the server into an empty folder: "Install server" in the Forge installer, the command below for NeoForge, or the executable server jar for Fabric.
3. 3Copy the mods and config folders from the pack's profile folder in the CurseForge app into the server folder, plus any other folder the pack adds, such as kubejs or scripts.
4. 4Take out client-only mods. The server is missing the game's client code, so a mod that calls it crashes the server at start. Modrinth shows client and server support on each mod's page.
5. 5Start the server once, accept the EULA in eula.txt, and start it again.

For NeoForge, the installer runs from the command line. This is the NeoForge version All the Mods 10 uses:

java -jar neoforge-21.1.251-installer.jar --installServer

Forge 1.17.1 and newer, and NeoForge, read the server's RAM from user_jvm_args.txt, which ships the line commented out as # -Xmx4G: remove the # and set the number to your pack's figure from the RAM table below. For older Forge such as 1.12.2, and for Fabric, the RAM goes in the launch command. This one starts a Cobblemon server on Minecraft 1.21.1 and Fabric Loader 0.19.5 with 6 GB:

java -Xmx6G -jar fabric-server-mc.1.21.1-loader.0.19.5-launcher.1.1.2.jar nogui

Let your friends connect

Friends on your home network join with your PC's local IP address, and no router change is needed. Everyone else needs port 25565 (TCP) forwarded to your PC in your router, then joins with your public IP.

Forwarding does not work on every connection, and a home IP address can change. Our vanilla server guide covers both, and the router steps are the same for a modded server.

How much RAM a modded server needs

RAM follows the pack more than the player count. CraftLands sizes each pack from a floor, the memory the pack needs with nobody online, plus about 0.2 GB for each player online at the same time. These figures come from our pack pages, checked on 30 September 2026:

On your own PC, set -Xmx to that figure and leave memory free for everything else: the operating system and, if you play on the same machine, the game client with its own allocation.

For another pack or player count, the RAM calculator runs the same sum. Each pack page has it built in as well, for example Prominence II server hosting and Craft to Exile 2 server hosting.

Installing a modpack on a CraftLands server

If the server should stay up when your PC is off, the CraftLands panel installs the pack with its loader and Minecraft version matched, so the Java, installer and file steps above fall away. The steps from our modpack install guide:

1. 1In the panel's left sidebar, open Modpacks under the Minecraft section.
2. 2Set the provider in the top right corner to CurseForge.
3. 3Pick the pack.
4. 4In the prompt, choose the pack version your players have. Tick Wipe Server Files only if you want the server cleared first.
5. 5Click Install in the bottom right of the prompt, then restart the server.

The installer switches the server type (the egg) by itself, so there is nothing to change on the Startup page. A pack you built yourself goes up as a .zip through the Custom button on the same page: see upload a custom modpack.

Every pack with a ready setup and its own RAM guide is listed under modded Minecraft server hosting, and any other CurseForge pack installs through the panel the same way. You can move to another RAM size or another pack from the panel later.

Cobblemon

Fabric · 1.21.1

Deploy

Fabric pack: 4 GB before anyone joins, about 6 GB with 10 players online.

SkyFactory 4

Forge · 1.12.2

Deploy

Forge 1.12.2 skyblock pack: 4 GB floor, about 6 GB with 10 players online.

RLCraft

Forge · 1.12.2

Deploy

Forge 1.12.2: 6 GB floor, about 8 GB with 10 players online.

Prominence II

Fabric · 1.20.1

Deploy

Fabric 1.20.1: 6 GB floor, about 8 GB with 10 players online.

Craft to Exile 2

Forge · 1.20.1

Deploy

Forge 1.20.1: 8 GB floor, about 10 GB with 10 players online.

All the Mods 10

NeoForge · 1.21.1

Deploy

NeoForge 1.21.1: 12 GB floor, about 14 GB with 10 players online.

GT New Horizons (GTNH)

Forge · 1.7.10

Deploy

Forge 1.7.10: 6 GB early game, then about 0.5 GB per player.

Common problems

• Kicked at login with a list of mods. The player's pack version differs from the server's. Install the same pack version on both sides.
• The server crashes on start and names a client class. A client-only mod is in the server's mods folder. Remove it and start again.
• The server will not start at all. Check the Java version against the table above before anything else.
• Long freezes, then an out-of-memory error. The server has less RAM than the pack's floor. Raise -Xmx to at least the figure in the RAM table.
• Lag with RAM to spare. Minecraft runs 20 ticks a second, 50 ms each, and the server falls behind when a tick takes longer. That time goes on machines, mobs and new chunks, so more RAM does not fix it. Pre-generating the area around spawn before the first session takes new chunks out of the picture.

Frequently Asked Questions

Where to go next

To choose the pack first, our guide to the best Minecraft modpacks sorts them by playstyle with the RAM each one needs.