The easiest way to host a small Project Zomboid session is the in-game Host menu. If the world must remain available after the host closes the game, install the free dedicated-server tool (Steam app 380870) and run it on a home PC, a separate machine, or a managed server. Remote players normally need UDP ports 16261 and 16262 allowed through the host firewall and forwarded on the router. This guide covers both hosting methods, dedicated-server installation on Windows and Linux, first-run configuration, networking, mods, backups, updates, and the fixes for the most common connection failures.
Which Project Zomboid hosting method should you use?
Use Host when one player can keep the game running and the group is small. Use a dedicated server when the world should keep running while the host is offline, when gameplay performance should be separated from the server process, or when you need stronger control over settings, backups, and administration.
| Option | Persistence when the host is offline | Setup and networking | Administration | Where it runs |
|---|---|---|---|---|
| In-game Host | Stops when the host closes the session | Fastest setup; the host still needs to handle local networking for remote players | Settings are managed from the game interface | The host’s gaming PC |
| Dedicated process | Continues running after the game client closes | Requires server installation, firewall rules, and usually router forwarding | Manual control of INI files, saves, logs, mods, updates, and backups | The same PC, another home machine, or a rented server |
When the in-game Host menu is enough
Choose Host if your group plays together at the same times and nobody needs to join while the host is away. It avoids a separate server installation and is practical for a short-lived cooperative world. The trade-off is that the host’s game must remain open, and the same computer handles both rendering and server work.
When a dedicated server is the better choice
A dedicated process is the persistent option. It can run on a spare Windows or Linux machine, a headless box, or a rented server panel while everyone connects with the normal game client. It also gives you direct control over admission, player slots, PvP, pausing, spawn regions, Workshop content, and scheduled maintenance. You become responsible for patching, backups, uptime, and troubleshooting.
What do you need before installing a dedicated server?
Prepare the machine, network, and game version before you install anything. A dedicated server does not remove the need for compatible clients: everyone must use the same branch and build, and modded players must have matching content.
- A Windows or Linux machine that can stay online for the sessions you want to host.
- A Steam account for the normal Steam installation, or SteamCMD for a headless installation.
- Permission to open UDP ports on the host firewall and configure port forwarding on the router if players connect from outside your LAN.
- A fixed or reserved private LAN address for the server machine, so a router rule does not break after a DHCP address change.
- The same Project Zomboid branch and build on the server and every client. Do not mix Build 41 and Build 42 worlds or branches.
- A backup location with enough space for the complete
Zomboidfolder, including saves, settings, logs, and mod configuration.
How do you install the Project Zomboid dedicated-server software?
The dedicated server is a free download distributed as Steam app 380870. You can install it through Steam’s Tools library or use SteamCMD on a machine without the Steam desktop client.
Install through Steam on Windows
- Open Steam and select Library.
- Use the library filter or search to show Tools.
- Find Project Zomboid Dedicated Server and install it.
- Open the installation folder. The server is launched with the files shipped there; do not press the ordinary Steam Play button for the game client as a substitute launcher.
Install with SteamCMD on a headless machine
Install SteamCMD, choose a server directory, and run the following commands in SteamCMD. Replace the path with the folder you want to contain the server files.
force_install_dir <server-folder>
login anonymous
app_update 380870 validate
quitapp_update 380870 validate downloads or updates the dedicated-server files and checks their integrity. Run it again when you intentionally update a SteamCMD installation, and record the resulting server build so clients can be kept on the same version.
Which file starts the server?
Run the script supplied in the server folder. On Windows the usual launcher is StartServer64.bat. On Linux it is start-server.sh. A normal Steam game launch starts the client, not the dedicated process, and will not create the same server profile.
What happens on the first server launch?
Start the supplied script once and follow the console prompts. The first run asks you to create an administrator password, creates the default profile, and starts the world. The profile is normally named servertest.
The active profile is stored in the user’s Zomboid data directory, separate from the directory containing the server executable. This distinction matters: editing a copy beside the executable may have no effect if the running process is loading the profile from the user folder.
How much memory should the server use?
On Windows, the shipped batch file uses -Xms16g -Xmx16g. On Linux, the documented shipped configuration includes an -Xmx8g value in ProjectZomboid64.json. These are starting values supplied by the server package, not a promise that every machine needs or can reserve that amount.
If the host cannot reserve the configured memory, lower the values before launching. Do not blindly increase the heap when the machine is already swapping, stuttering, or crashing; more heap cannot fix a shortage of physical memory or an overloaded CPU. Change one setting at a time and observe whether the server completes startup and remains stable under the real player and mod load.
Where are the Project Zomboid server files and saves?
On a default profile, the important files are in the user’s Zomboid directory:
| Purpose | Windows location | Linux location |
|---|---|---|
| Server settings and profile files | %USERPROFILE%ZomboidServer |
~/Zomboid/Server |
| General profile name | servertest |
servertest |
| Multiplayer save | Zomboid/Saves/Multiplayer/servertest |
Zomboid/Saves/Multiplayer/servertest |
The core files for the default profile are servertest.ini, servertest_SandboxVars.lua, servertest_spawnpoints.lua, and servertest_spawnregions.lua. If you rename the profile, replace servertest in each filename and path with the profile name the server actually loads.
How do you configure the server in the INI file?
Stop the server before editing its live files. Open the INI belonging to the active profile, make a copy, change only the settings you understand, and restart the process to apply them. The generated INI and the exact server build are authoritative when documentation differs between branches.
| Setting | What it controls |
|---|---|
Public=true or false |
Whether the server is presented as public rather than private. |
PublicName |
The listing name players see. |
PublicDescription |
Descriptive text for the listing. |
Password |
The password required to join. |
Open |
Whether the server accepts players without the restrictions imposed by a closed or whitelist configuration. |
MaxPlayers |
The configured player-slot limit. |
PVP |
Whether player-versus-player damage and rules are enabled. |
PauseEmpty |
Whether the world pauses when no players are connected. |
| RCON fields | Remote-console administration; configure these only when you deliberately need RCON and have secured its access. |
How many players can the server support?
Published limits vary by build. ForgeWorld Gaming lists a default MaxPlayers=32 and an allowed range of 1–100, while later Build 42 documentation describes different handling. Treat the value generated in your own INI and the server’s build as the source of truth. A slot number is not a performance guarantee: test the actual map, simulation settings, mods, and internet connection with the workload you expect.
How should you choose admission settings?
Set a join password even for a private group, and keep Open and whitelist behavior consistent with your plan. If players are rejected immediately, verify these settings before changing unrelated world options. For a public listing, choose a clear name and description and monitor who is allowed to join.
Which ports does Project Zomboid use, and how do you forward them?
For a normal remote setup, allow and forward both ports as UDP. Permit them in the operating-system firewall, then create router rules that send them to the server machine’s private LAN address.
| Port | Protocol | Role |
|---|---|---|
| 16261 | UDP | Default player-facing server port. |
| 16262 | UDP | Second/direct connection port used by the server. |
- Give the server computer a reserved DHCP lease or otherwise note its current private address, such as
192.168.1.50. - In the host firewall, create inbound UDP rules for ports
16261and16262. - In the router’s port-forwarding page, forward UDP
16261and UDP16262to that private address. - Start the server and wait for the console to report that it has started.
- Test a join from the same LAN first. Then have someone outside the LAN use the public IPv4 address, the server port, and the join password in the game’s multiplayer/favorites flow.
If you run a second server on the same machine, it cannot reuse the same pair. Assign that instance its own player-facing and direct-connection ports and forward the additional pair to the same private address.
How does a player join the server?
After the server has finished starting, open Project Zomboid’s multiplayer browser or favorites flow. The remote player enters the host’s public IPv4 address, the configured port, and the join password. Players on the same home network should use the server’s private LAN address for the local test.
If a local player can connect but an outside player cannot, the game settings are probably valid and the remaining suspects are the host firewall, router forwarding, carrier-grade NAT, or an incorrect public address. Confirm the forwarding destination has not changed and that both rules are UDP, not TCP.
How do you install and synchronize mods?
A dedicated server does not infer a complete mod setup from one client’s subscription list. Every server-side Workshop item and mod ID must be declared, and the clients must have compatible files.
- Stop the server and back up the complete Zomboid folder.
- Add each numeric Workshop ID to
WorkshopItems=in the active profile’s INI. - Add each mod identifier to
Mods=. - Keep the lists, load order, branch, and client files aligned. A Workshop ID identifies the downloaded item; the mod ID is the identifier the game loads, so do not substitute one for the other.
- Restart the server and inspect the console for download or load errors.
- Have a test player join before adding another batch. If the server breaks, remove half the recently added entries, test again, and repeat the split until the offending item is isolated.
Change mods in small batches and retain a known-good backup. A map or gameplay mod can alter the save, so removing it later may not safely undo its changes. Keep a written record of the exact Workshop and mod lists used by each working build.
How do you update the server without losing the world?
Updates, map changes, and mod changes are the moments when a backup matters most. Stop the process cleanly before copying files or editing configuration; never copy a live save while the server is writing to it.
- Announce maintenance and let players leave normally.
- Stop the dedicated process and wait for the console to close.
- Copy the entire
Zomboidfolder, includingSaves,Server, logs, and mod-related configuration, to a separate location. - Record the exact client and server build strings and the current Workshop and
Modslists. - For a SteamCMD installation, run
app_update 380870 validatebefore restarting. - Start the server, test an administrator login and a normal player join, and only then invite the full group.
Keeping the entire Zomboid folder as the backup unit makes migration to another machine possible because it preserves both the world and the profile that tells the server how to load it. Do not assume that copying only the executable directory includes the save.
What should you check when nobody can join?
The server starts, but everyone is rejected
- Confirm every client and the server use the same branch and exact build.
- Check the active profile’s
Open, whitelist behavior, andPassword. - Verify that players are entering the correct address and port for their location: private LAN address inside the home network, public IPv4 address from outside.
- Make sure the server is loading the INI you edited, not a differently named profile.
LAN players connect, but internet players cannot
- Allow inbound UDP
16261and16262in the host firewall. - Forward both UDP ports to the server’s current private address.
- Check that the router rule points to the right machine after any DHCP change.
- Test from a genuinely external network; testing the public address from inside the same LAN can fail on routers without NAT loopback.
The server will not start after a mod change
- Compare
WorkshopItemsandModsseparately rather than assuming they are interchangeable. - Check for a typo, a missing Workshop download, an incompatible branch, or a changed load order.
- Remove half of the newly added entries, restart, and repeat the process to identify the offending mod.
- Restore the known-good Zomboid backup if the save or map was changed and the failure cannot be isolated safely.
The process crashes or the machine swaps heavily
- Lower the configured heap before launch if the host cannot reserve the shipped memory values.
- Stop other memory-intensive applications and check available physical RAM.
- Do not increase
-Xmxsimply because a crash occurred; first determine whether the problem is memory pressure, a mod, a build mismatch, or a corrupted installation.
How do you move the server to another machine?
Stop the old server, copy the complete Zomboid folder, install the same server build on the destination, and place the profile and save where that installation expects them. Keep the profile name unchanged unless you also rename every matching INI, sandbox, spawn, and save path. Update the router’s forwarding destination to the new machine, then test locally before changing the public address shared with players.
Is a rented managed server worth using?
A managed Project Zomboid host can be practical when you cannot forward ports, do not have a machine that can stay online, or do not want to maintain updates and backups. You trade direct operating-system access for a control panel and the provider’s uptime and maintenance model. Before paying, verify the supported Project Zomboid branch, backup and restore process, mod controls, player-slot policy, geographic location, and whether you can download your complete Zomboid folder for migration.
Frequently Asked Questions
Can I host Project Zomboid from the same PC that I play on?
Yes. Run the dedicated process on the gaming PC and launch the game client separately, provided the machine has enough CPU, memory, and network capacity. The in-game Host option is simpler, but it ends when the host closes the session.
Do Project Zomboid server ports use TCP or UDP?
The normal player-facing and direct-connection rules use UDP: 16261 and 16262. Creating only TCP rules will not make the standard remote connection work.
Will my existing single-player world become a dedicated multiplayer world automatically?
No. The dedicated server creates and loads its own multiplayer save under the profile path, such as Zomboid/Saves/Multiplayer/servertest. Treat a single-player save conversion as a separate migration task and keep a backup before experimenting.
What happens if the server and clients are on different Project Zomboid builds?
The mismatch can prevent joining or cause incompatible world and mod behavior. Record the exact build string on both sides and move every player and the server to the same branch before troubleshooting ports or passwords.
How often should I back up a Project Zomboid server?
Back up before every game update, map or mod change, and migration. For an active long-running world, keep periodic dated copies as well as a known-good pre-change backup so you can recover from corruption or an incompatible Workshop update.