Project Zomboid Multiplayer Server Hosting Guide: Setup and Configuration

Why Host a Project Zomboid Server?

Project Zomboid is one of the deepest zombie survival sandboxes available, and multiplayer transforms the experience. A dedicated server keeps your Knox County world persistent: bases stay built, loot remains where you left it, and zombie hordes continue roaming whether players are online or not. A hosted server lets your community log in on their own schedule and build a shared survival story together.

Choosing Your Build Version

Project Zomboid currently has two active versions that matter for server hosting:

• Build 41 (Stable): The proven, polished branch. Full mod support through Steam Workshop. Reliable for large multiplayer communities with 32+ players.
• Build 42 (Unstable): The massive update with crafting, animals, farming, and new game modes. Multiplayer was added in December 2025. The developers recommend a maximum of 20 players per server and advise disabling all mods.

Your choice depends on your community’s priorities. If you want stability, mod support, and proven performance, stay on Build 41. If your group wants to experience the new crafting systems, animals, and game modes, Build 42 multiplayer is playable but expect occasional issues.

System Requirements

Hardware

• CPU: Quad-core processor at 2.4 GHz or higher
• RAM: 4 GB minimum for small servers, 8-16 GB for larger populations or Build 42
• Storage: 10 GB SSD recommended
• Network: Stable connection with low latency

Required Ports

Forward these ports through your router and firewall:

• TCP 16261 - Main game connection
• UDP 16262 - Player slot 1 (add one UDP port per additional player slot, e.g., 16263 for slot 2, 16264 for slot 3)

For example, a 16-player server needs TCP 16261 and UDP 16262-16277 open.

Hosting Options

Managed Hosting

A hosting provider manages the hardware, networking, updates, and backups. You configure game settings and play. This is the recommended approach for most communities because it eliminates the overhead of server maintenance.

Reactor offers Project Zomboid server hosting with support for both Build 41 and Build 42. Features include Steam Workshop mod integration, automatic backups, and full sandbox customization.

Self-Hosted via SteamCMD

Download the server files for free through SteamCMD. This approach gives full control but requires managing your own hardware, ports, updates, and troubleshooting.

Self-Hosted Installation

Step 1: Install SteamCMD

Download SteamCMD and extract it to a dedicated folder on your server machine.

Step 2: Download Server Files

steamcmd +login anonymous +app_update 380870 validate +quit

App ID 380870 is the Project Zomboid Dedicated Server. For Build 42 unstable, add the beta flag:

steamcmd +login anonymous +app_update 380870 -beta unstable validate +quit

Step 3: First Launch and Configuration

Run the server start script. On first launch, it generates the default configuration files and world data. The server will prompt you to set an admin password. After initialization, shut down the server to edit configuration files.

Step 4: Configure Server Settings

The primary configuration file is servertest.ini (or your custom server name) in the server’s data directory. Key settings include:

• DefaultPort: Base port (default 16261)
• MaxPlayers: Maximum simultaneous players
• PVP: Enable or disable player-versus-player combat
• PauseEmpty: Pause the game when no players are online
• Open: Allow anyone to join, or restrict to whitelisted accounts
• Password: Server password for private communities
• PublicName: Server name displayed in the browser
• Map: Map selection (default Muldraugh, KY)
• GlobalChat: Enable or disable global chat channel
• ServerPlayerID: Unique server ID for character persistence

Step 5: Sandbox Settings

Sandbox settings control the actual gameplay experience: zombie population, loot rarity, weather, farming speed, and hundreds of other parameters. These are stored in a separate sandbox variables file associated with your world save.

For detailed sandbox configuration, see our best Project Zomboid server settings guide.

Server Administration

Admin Commands

Connect to your server and use these commands in the chat window (prefix with /):

• /adduser [username] [password] - Create a new account
• /addusertowhitelist [username] - Whitelist a player
• /banuser [username] - Ban a player
• /kickuser [username] - Kick a player
• /grantadmin [username] - Give admin privileges
• /servermsg [message] - Broadcast a message to all players
• /changeoption [option]=[value] - Change server settings live
• /reloadoptions - Apply changed options without restart
• /save - Force a world save
• /quit - Save and shut down the server

Mod Management

On Build 41, Steam Workshop mods can be added to the server by listing their Workshop IDs in the server configuration. Players connecting to the server will automatically download required mods.

On Build 42, The Indie Stone recommends disabling all mods for multiplayer stability. As Build 42 matures, mod compatibility will improve.

Backup Strategy

Project Zomboid worlds grow in size as players explore. Regular backups are essential. The world save directory contains all map data, player profiles, and sandbox settings. Back up the entire save folder on a daily schedule at minimum.

With Reactor hosting, automatic backups run on schedule with seven days of retention, and manual backups can be triggered at any time.

Build 42 Multiplayer Considerations

If you choose to run a Build 42 server, keep these developer recommendations in mind:

• Player limit: Keep servers at 20 players or fewer
• Mods: Disable all mods, including client-side
• Saves: Build 42 saves are not compatible with Build 41 and may break between unstable updates
• Ragdoll: Not available in multiplayer
• Debug mode: Disabled during multiplayer sessions
• Performance: Monitor server performance closely as Build 42 is still being optimized

Despite these limitations, Build 42 multiplayer brings a fundamentally richer experience with crafting, animals, hunting, and expanded farming that makes cooperative survival more engaging than ever.

Connecting to Your Server

Players can find your server in the in-game server browser by searching for the server name, or connect directly via IP address and port. First-time connections require creating an account on the server (username and password) unless the server is configured for open access.

For a deep dive into recent game changes, read our Project Zomboid 2025 updates overview.