{"id":3815,"date":"2026-10-27T17:11:36","date_gmt":"2026-10-27T14:11:36","guid":{"rendered":"https:\/\/gameteam.io\/blog\/project-zomboid-dedicated-server-guide\/"},"modified":"2026-10-27T17:11:36","modified_gmt":"2026-10-27T14:11:36","slug":"project-zomboid-dedicated-server-guide","status":"publish","type":"post","link":"https:\/\/gameteam.io\/blog\/project-zomboid-dedicated-server-guide\/","title":{"rendered":"Project Zomboid Dedicated Server: How to Host One (Build 42 Setup, Requirements, Ports)"},"content":{"rendered":"

A Project Zomboid dedicated server is a copy of the game’s world that runs on its own, so your group’s Knox County stays online whether or not the person who set it up is playing.<\/strong> You can host one yourself with the free Project Zomboid Dedicated Server tool (Steam app 380870) on a Windows or Linux machine with 4\u20138 GB of RAM to spare, open UDP ports 16261 and 16262, and set it up in servertest.ini<\/code>. Build 42 has had multiplayer since 42.13 and became the stable version on July 29, 2026, so this guide is written for Build 42, with notes where Build 41 differs.<\/p>\n

Host button or dedicated server: which one do you need?<\/h2>\n

Project Zomboid gives you two ways to play online. The Host button on the main menu starts a server on your own PC while you play, and friends join through a Steam invite. A dedicated server runs as its own program on a spare PC, a VPS or a rented server, stays up after you log off, and lets anyone with the address and password join. If you have more than a few players, or people play at different times, set up a dedicated server.<\/p>\n\n\n\n\n\n\n\n\n\n\n
<\/th>\nHost button (co-op, non-dedicated)<\/th>\nDedicated server<\/th>\n<\/tr>\n<\/thead>\n
Where it runs<\/td>\nYour PC, next to your game<\/td>\nIts own process on any machine<\/td>\n<\/tr>\n
Online when the host quits<\/td>\nNo<\/td>\nYes<\/td>\n<\/tr>\n
How friends join<\/td>\nSteam invite from the Invite Friends screen<\/td>\nIP, port and server password<\/td>\n<\/tr>\n
Memory<\/td>\n“Server memory” on the Host screen<\/td>\n-Xmx<\/code> in the start script<\/td>\n<\/tr>\n
Settings<\/td>\n“Manage settings\u2026” on the Host screen<\/td>\nservertest.ini<\/code> and servertest_SandboxVars.lua<\/code><\/td>\n<\/tr>\n
Log to check when it breaks<\/td>\nZomboid\/coop-console.txt<\/code><\/td>\nZomboid\/server-console.txt<\/code><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

How to host a co-op game for friends:<\/strong> choose Host from the main menu, set up the world with Manage settings\u2026<\/em>, pick a Server memory<\/em> value, then start. Once you’re in, invite friends from the Invite Friends screen. A friend who tries to join without an invite sees “The host must allow you to join”. Everything from here on is about the dedicated server.<\/p>\n

Project Zomboid dedicated server requirements<\/h2>\n

The dedicated server has no Steam store page and no published minimum spec, so size it by what it does. Give the server process 4\u20138 GB of RAM on its own, plus about 7 GB of disk for the install and more for saves, backups and mods. Use a modern 64-bit CPU and a connection whose upload can carry your group. It runs on Windows or Linux, and Steam also ships a macOS build of the tool.<\/p>\n\n\n\n\n\n\n\n\n
Your server<\/th>\nServer memory to start with<\/th>\n<\/tr>\n<\/thead>\n
2 players, vanilla<\/td>\n4 GB<\/td>\n<\/tr>\n
4\u20135 players, a few mods<\/td>\n4\u20136 GB<\/td>\n<\/tr>\n
Around 10 players, or a mod list<\/td>\n6\u20138 GB<\/td>\n<\/tr>\n
20\u201332 players spread across the map, or a big mod list<\/td>\n8 GB and up<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Memory climbs as players spread out, because the server keeps the map loaded around each of them, and an old world uses more than a fresh one. If you host on the PC you also play on, remember the game wants its own share on top. Running a dedicated server without your own hardware is what Project Zomboid server hosting<\/a> is for.<\/p>\n

What is server memory in Project Zomboid?<\/h3>\n

Server memory is the most RAM the Java process running the server may use. On the Host screen it is the Server memory<\/em> dropdown, 4 GB by default on 64-bit systems since Build 41.71, and it is saved in Zomboid\/Lua\/host.ini<\/code>. On a dedicated server it is the -Xmx<\/code> value: in StartServer64.bat<\/code> on Windows, and in ProjectZomboid64.json<\/code> in the server folder on Linux. Too little and the server stutters or crashes as the map fills in. Ask for more than the machine has free and it won’t start at all.<\/p>\n

How to set up a Project Zomboid dedicated server<\/h2>\n

Install the server tool through Steam or SteamCMD and start it once. That first start creates the config files and asks you for an admin password. Then stop it, edit servertest.ini<\/code>, and start it again. The steps are the same on Windows and Linux apart from the start script. You don’t need to own anything extra: Steam lets anyone download app 380870.<\/p>\n

Option A: Windows, through Steam<\/h3>\n
    \n
  1. In your Steam library, switch the filter to Tools<\/em> and install Project Zomboid Dedicated Server<\/strong>.<\/li>\n
  2. Right-click it, choose Manage \u2192 Browse local files<\/em>, and run StartServer64.bat<\/code>.<\/li>\n<\/ol>\n

    Option B: Windows or Linux, through SteamCMD<\/h3>\n
      \n
    1. Install SteamCMD, Valve’s command-line Steam client.<\/li>\n
    2. Download the server. On Linux, use a normal user rather than root:\n
      steamcmd +force_install_dir \/opt\/pzserver +login anonymous +app_update 380870 validate +quit<\/code><\/pre>\n
          On Windows, swap the folder for something like C:\\pzserver<\/code>. Run the same command again later to update.<\/li>\n
    3. Start the server: StartServer64.bat<\/code> on Windows, or .\/start-server.sh<\/code> from the install folder on Linux. Run it inside tmux<\/code> or screen<\/code> so it keeps running when you close the terminal.<\/li>\n<\/ol>\n
      First start: create the admin account<\/h3>\n
      On a brand-new server the console stops and asks Enter new administrator password:<\/code>, then Confirm the password:<\/code>. That creates an account called admin<\/code>, which you can log in with from the game. To skip the prompt, add -adminpassword yourpassword<\/code> to the start command. When the console reports the server has started, type quit<\/code> to save and stop it, then edit the config.<\/p>\n
      Where are the Project Zomboid server files?<\/h3>\n
      The program and your data live in different places. The data folder is C:\\Users\\<you>\\Zomboid<\/code> on Windows and ~\/Zomboid<\/code> on Linux, and -cachedir=<\/code> moves it elsewhere.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n
      What<\/th>\nLocation<\/th>\n<\/tr>\n<\/thead>\n
      Server program<\/td>\nsteamapps\/common\/Project Zomboid Dedicated Server<\/code>, or your SteamCMD folder<\/td>\n<\/tr>\n
      Server settings<\/td>\nZomboid\/Server\/servertest.ini<\/code><\/td>\n<\/tr>\n
      Sandbox (world) settings<\/td>\nZomboid\/Server\/servertest_SandboxVars.lua<\/code><\/td>\n<\/tr>\n
      Spawn regions and points<\/td>\nZomboid\/Server\/servertest_spawnregions.lua<\/code>, servertest_spawnpoints.lua<\/code><\/td>\n<\/tr>\n
      The world save<\/td>\nZomboid\/Saves\/Multiplayer\/servertest\/<\/code><\/td>\n<\/tr>\n
      Player accounts and whitelist<\/td>\nZomboid\/db\/servertest.db<\/code><\/td>\n<\/tr>\n
      Automatic backups<\/td>\nZomboid\/backups\/<\/code><\/td>\n<\/tr>\n
      Server log<\/td>\nZomboid\/server-console.txt<\/code><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
      “servertest” is only the default name. Start the server with -servername friends<\/code> and it uses friends.ini<\/code>, friends_SandboxVars.lua<\/code> and a friends<\/code> save folder instead, which is how you run several worlds from one install. Give each one its own DefaultPort<\/code> and UDPPort<\/code>.<\/p>\n
      Set the server memory<\/h3>\n
      On Windows, open StartServer64.bat<\/code> in a text editor and change the number after -Xmx<\/code>, for example -Xmx6g<\/code> for 6 GB. Keep -Xms<\/code> at or below it. On Linux, change the -Xmx<\/code> entry in ProjectZomboid64.json<\/code>. Leave a couple of GB for the operating system.<\/p>\n
      Project Zomboid server ports<\/h2>\n
      A Project Zomboid server needs two UDP ports: 16261, the game port players connect to, and 16262, the direct-connection port. Forward both to the server machine and allow both through its firewall. RCON uses TCP 27015 but only listens once you set an RCON password, and you don’t need it to play.<\/p>\n\n\n\n\n\n\n\n
      Port<\/th>\nProtocol<\/th>\nSetting<\/th>\nUsed for<\/th>\n<\/tr>\n<\/thead>\n
      16261<\/td>\nUDP<\/td>\nDefaultPort<\/code><\/td>\nThe port players enter; also answers Steam queries<\/td>\n<\/tr>\n
      16262<\/td>\nUDP<\/td>\nUDPPort<\/code><\/td>\nDirect connection between game and server<\/td>\n<\/tr>\n
      27015<\/td>\nTCP<\/td>\nRCONPort<\/code><\/td>\nRemote console, off until RCONPassword<\/code> is set<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
      Windows Firewall, from an administrator Command Prompt:<\/p>\n
      netsh advfirewall firewall add rule name=\"Project Zomboid 16261\" dir=in action=allow protocol=UDP localport=16261\nnetsh advfirewall firewall add rule name=\"Project Zomboid 16262\" dir=in action=allow protocol=UDP localport=16262<\/code><\/pre>\n
      Linux with ufw: sudo ufw allow 16261\/udp<\/code> and sudo ufw allow 16262\/udp<\/code>. On your router, forward both ports, UDP, to the server’s local IP. UPnP=true<\/code> (the default) tries to set up the forward on its own and falls back to the default ports if it can’t. To use other ports, change DefaultPort<\/code> and UDPPort<\/code>, or start the server with -port<\/code> and -udpport<\/code>.<\/p>\n
      “Server has port 16262 closed”?<\/strong> Since Build 41.77, the game tries a direct connection on the second port first. If that fails it connects through Steam and warns “SERVER HAS PORT 16262 CLOSED. PERFORMANCE MAY BE SEVERELY AFFECTED”<\/em>. Forward 16262 UDP as well as 16261 and the warning goes away.<\/p>\n
      How to join a Project Zomboid server (and invite friends)<\/h2>\n
      From the main menu choose Join<\/em>, then add the server’s IP and port (16261 unless you changed it), the server password if there is one, and an account username and password for yourself, and click Join Server<\/em>. On an open server, the first time you connect creates that account, so friends need nothing from you but the address and password.<\/p>\n
        \n
      1. Players outside your home use your public IP. Players on the same network as the server use its local IP.<\/li>\n
      2. Save it with Add to favorites<\/em> so it shows on the Favorites tab next time.<\/li>\n
      3. To list it publicly, set Public=true<\/code> and it appears in the in-game Internet list. Steam servers always show in Steam’s own server browser.<\/li>\n<\/ol>\n
        Two passwords get mixed up a lot. The server password<\/strong> (Password=<\/code> in servertest.ini<\/code>) is the same for everyone. The account password<\/strong> belongs to each player and stops someone else taking their username. Get the first one wrong and you see “Wrong server password given”.<\/p>\n
        The settings to change first<\/h2>\n
        Open Zomboid\/Server\/servertest.ini<\/code> with the server stopped and set the basics. Zombie numbers, speed, loot and day length are not in this file: they are sandbox options in servertest_SandboxVars.lua<\/code>, which the server reads every time it starts.<\/p>\n
        PublicName=Knox Survivors\nPassword=pick-a-password\nMaxPlayers=12\nOpen=true\nPVP=false\nPauseEmpty=true<\/code><\/pre>\n
        MaxPlayers<\/code> defaults to 32, and the game warns that higher counts can cause poor map streaming and desync. For a roleplay (RP) or PvE community, set Open=false<\/code> to make it whitelist-only and create accounts with \/adduser<\/code>. Every option, including the sandbox ones and why settings sometimes don’t save, is in Project Zomboid server settings explained<\/a>.<\/p>\n
        How to add mods to a Project Zomboid dedicated server<\/h2>\n
        Each Steam Workshop mod needs two entries in servertest.ini<\/code>: its Workshop ID in WorkshopItems=<\/code> and its mod ID in Mods=<\/code>, each list separated by semicolons. On every start the server downloads the listed Workshop items before it loads the world, and players are asked to download the same items when they join. Leave out either list and the mod silently does nothing. Map mods also add their folder name to Map=<\/code>. The step-by-step version, with Build 42 compatibility and the errors you’ll meet, is how to add mods to a Project Zomboid server<\/a>.<\/p>\n
        Becoming admin and using commands<\/h2>\n
        Log in with the admin<\/code> account from the first start, or give your own account the role from the server console with setaccesslevel \"yourname\" admin<\/code>. In game, admins type commands into chat with a slash (\/players<\/code>, \/kickuser<\/code>, \/save<\/code>) and get an Admin Panel. In the console you type the same commands without the slash. The full list is in Project Zomboid server commands<\/a>.<\/p>\n
        Build 42 vs Build 41 servers<\/h2>\n
        Build 42 (B42) is now the default. Multiplayer came back in unstable 42.13 in December 2025, Build 42.20 replaced Build 41 as the stable version on July 29, 2026, and 42.21 followed on September 28. Build 41 saves don’t load in Build 42. If your group wants to stay on Build 41, move the server and every player to the legacy41<\/code> beta branch.<\/p>\n