Setting up a Project Zomboid server (Build 42)

Since 29 July 2026, Build 42 (with multiplayer) is Project Zomboid's stable version, and SteamCMD installs it with nothing special. It needs more memory than 41: 8 GB is tight; for a group with mods, 10 to 12 GB is better.

1. Download it

# Windows
C:\steamcmd\steamcmd.exe +force_install_dir C:\zomboid +login anonymous +app_update 380870 validate +quit

# Linux (as the steam user)
~/steamcmd/steamcmd.sh +force_install_dir ~/zomboid +login anonymous +app_update 380870 validate +quit

2. First start

# Windows
C:\zomboid\StartServer64.bat

# Linux
~/zomboid/start-server.sh

The first time, the console asks for a password for the admin user. Write it down: you will log in as administrator with that user and password. When it finishes starting, stop it with quit to configure it.

3. Memory

It is set with the -Xmx value:

Windows: inside StartServer64.bat.
Linux: in ProjectZomboid64.json, in the vmArgs list.

For example, -Xmx10g on a 12 GB VPS. Always leave headroom for the system.

4. Settings

They are stored in the Zomboid/Server folder of the user running it (on Windows, C:\Users\Administrator\Zomboid\Server\; on Linux, ~/Zomboid/Server/):

servertest.ini: general settings. PublicName (name), Public=true (appear in the list), Password, MaxPlayers, PVP...
servertest_SandboxVars.lua: the world rules (zombies, loot, days...).

Workshop mods: in servertest.ini, WorkshopItems= holds the Workshop numbers and Mods= each mod's identifier (the "Mod ID" on its page), all separated by semicolons with no spaces. If a mod does not load on Build 42, try a backslash in front of its ID in Mods=: some 42 versions required it.

5. Ports

Project Zomboid uses 16261 and 16262 on UDP:

# Windows (PowerShell as administrator)
New-NetFirewallRule -DisplayName "Zomboid UDP 16261-16262" -Direction Inbound -Protocol UDP -LocalPort 16261-16262 -Action Allow -Profile Any

# Linux
ufw allow 16261:16262/udp

6. Joining

In the game, Join: your VPS's IP, port 16261, and a username and password. Each player creates their account the first time they join (if the server is open); you log in as admin with the first-start password. To give someone else permissions: /setaccesslevel Name admin.