How to Make a Project Zomboid Dedicated Server on Your PC (Windows and Linux)

What you need before you start

A PC that stays on while you want to play: if it goes off, so does the server. Free memory for the server: with Build 42, 6 GB at least (on 4 GB we measured it with barely half a gig to spare), and more if you run lots of mods (how much RAM for your group). If you also play on that PC, the game needs its own memory on top.

About 7 GB of disk for the server, plus whatever the world takes up over time. And UDP ports 16261 and 16262 open on your router, unless your friends are on your own network.

If you only want to play for an evening, you don't need any of this: with Host, your own game acts as the server while you play (how to host with Host). A dedicated server is for keeping the world there even when you're not.

Installing it from Steam (Windows)

1. Find it under “Tools”

   In your Steam library, under “Tools”, you'll find “Project Zomboid Dedicated Server”. Install it like any other game: it's free.

2. Same branch as the game

   Right-click → Properties → “Game Versions & Betas”. Leave it on the same one as your game: the normal one for Build 42, legacy41 if you play Build 41. If they don't match, nobody gets in.

3. Don't start it with “Play”

   The server isn't launched from the Steam button but with its start-up file (see below). The official wiki warns that if you start it from Steam by mistake, you should verify the files (Properties → “Installed Files” → “Verify integrity of game files”).

Installing it with SteamCMD (Windows or Linux)

SteamCMD is Steam in text mode, the usual choice on a server without a screen. The Project Zomboid server is app 380870 and downloads with an anonymous login, without your account. On Linux, create a dedicated user for it and don't run it as root.

For Build 41, change the download line to app_update 380870 -beta legacy41 validate. The same command updates it later (when and how to update).

force_install_dir C:\PZServer
login anonymous
app_update 380870 validate
quit

Memory: set it before the first start

This is the number one failure. The start-up file has the memory Java will use hard-coded, and if it's more than your PC can give, the server never starts or shuts down with out-of-memory errors.

On Windows it's in StartServer64.bat, in the server folder (if you downloaded it with Steam, in steamapps\common\Project Zomboid Dedicated Server). Open it with Notepad and look for -Xms and -Xmx on the java line: they're the starting and maximum memory. For 6 GB, -Xms6g -Xmx6g. Save.

On Linux, start-server.sh reads the memory from ProjectZomboid64.json, in the same folder: it comes with -Xmx8g, and a game update puts it back to that. Change it to what you can spare, leaving some for the system: we leave 1 GB outside the Java heap on every server.

It's the same memory as the server memory setting on the Host screen: if a value worked for you there, the same one works here.

First start and the admin password

1. Start it

   On Windows, double-click StartServer64.bat (not StartServer64_nosteam, which is for playing without Steam). On Linux, inside tmux so it doesn't close if you lose the connection: bash start-server.sh.

2. Set the admin password

   The first time, the console asks for a password for the admin account the server creates. Write it down: it's the one you'll log in with to make yourself and your friends admin.

3. Wait for “SERVER STARTED”

   The first time, it generates the world and the settings files with the default values. When the console says the server has started, you can join. Don't close that window: it is the server.

4. Shut it down properly

   Type quit in that console (no slash): it saves and shuts down. Just closing the window can leave the last things you did unsaved.

Where the settings and the world live

In the Zomboid folder in your user profile (C:\Users\<your user>\Zomboid on Windows, ~/Zomboid on Linux). In Server you'll find servertest.ini (who can join, PvP, mods: what each option does), servertest_SandboxVars.lua (zombies, loot, power and water: the sandbox settings) and servertest_spawnregions.lua, with the zones where players can spawn. The world is in Saves\Multiplayer\servertest.

servertest is the default name. To have a different one (and a different world), add -servername name at the end of the java line in the .bat, or after bash start-server.sh on Linux: it will use name.ini and its own save folder.

Edit the files with the server stopped: the .ini is rewritten on shutdown. If you'd rather not touch files, the game itself edits them: with Host, the server settings are saved in that same folder, and if you name them servertest, the dedicated server uses them.

Opening the ports and joining

Open ports 16261 and 16262, both UDP, on your router towards the PC's IP, and let the server through Windows Firewall the first time it asks: the ports guide explains it step by step, including what to do if your provider uses CG-NAT.

Your friends join through “Join” → “Favorites” with your public IP and port 16261, and create their account when they join. You, on the same PC, can use that same IP; if it doesn't connect, try your local IP in the “Local IP” field. If someone is left out, these are the usual causes.

What it costs to run it at home

The software is free, but the PC has to stay on while you want to play (electricity included), your friends see your home IP, and updates, world backups and restarts are on you. With Build 42, the server also takes a good chunk of a normal PC's RAM.

On NapNodes

If you'd rather not keep a PC running, on NapNodes the dedicated server comes already installed: the Java memory adjusts itself to your server's on every start, the ports are open, the admin username and password are in “Settings” → “In-game admin”, and every .ini and SandboxVars setting is in “Settings”, each one explained and with a search box.

To try it without paying, there's the free Project Zomboid server: 6 GB, no card, and you start it when you want to play. And if you already have a world on your PC, it moves to the server by uploading a folder.

Frequently asked questions

More Project Zomboid guides

• Project Zomboid Private Server: Password and Whitelist
• Project Zomboid Server Lag: Causes and How to Fix It
• Free Project Zomboid Server: The Real Options and Their Catches

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