Project Zomboid Server and Sandbox Settings, Explained

Where the settings live

Everything is in Zomboid/Server/, in your user folder on a home PC (%USERPROFILE%\Zomboid\Server on Windows, ~/Zomboid/Server on Linux):

The world itself is saved in Zomboid/Saves/Multiplayer/servertest. "servertest" is the default server name; a server started with another name uses files with that name instead, so make sure you are editing the right ones.

What you can change mid-game

• Server options in servertest.ini can change at any time. Stop the server, edit, start it again — or edit while it runs and apply the file with the reloadoptions command.
• Sandbox options are read when the server starts, so restart after editing. Keep in mind that zombies and loot in areas players have already visited were generated with the old values: a change shows most clearly in places nobody has been yet.
• Some choices belong to a new world. The start date and the map are decided when the world is created. Changing the build — 41 to 42 — always means a new world.

Three sandbox presets that work

These are our suggestions, not the game's built-in presets. They use the option names you see on the Sandbox screen; the matching keys in servertest_SandboxVars.lua are listed underneath.

The keys behind them, as named in Build 42:

• Population — Zombies (1 Insane … 4 Normal, 5 Low, 6 None) and the finer ZombieConfig.PopulationMultiplier. Build 42's "Normal" is 0.65; Build 41's was 1.0, so do not copy numbers between builds.
• Respawn — RespawnHours, RespawnUnseenHours and RespawnMultiplier. Build 42 has respawn off by default; Build 41 had it on.
• Speed and infection — ZombieLore.Speed (1 Sprinters, 2 Fast Shamblers, 3 Shamblers, 4 Random) and ZombieLore.Transmission (1 Blood and Saliva, 2 Saliva Only, 3 Everyone's Infected, 4 None).
• Loot — Build 42 sets loot per category with multipliers from 0 to 4, such as FoodLootNew, WeaponLootNew and AmmoLootNew. Build 41 used FoodLoot, WeaponLoot and OtherLoot on a 1–5 rarity scale.
• XP — Build 42 uses MultiplierConfig.Global, with optional per-skill values. Build 41 used XpMultiplier.
• Time — DayLength, and WaterShut / ElecShut for when the water and power go off.

Multiplayer settings: PvP, safehouses, whitelist and more

These live in servertest.ini. Defaults are Build 42's.

Build 41 also had AutoCreateUserInWhiteList, which added every new player to the whitelist automatically; it is not part of Build 42's settings. To manage the whitelist itself, see the adduser commands in Project Zomboid admin commands.

Adding Workshop mods to a server

Every mod takes two lines in servertest.ini, and a custom map takes a third:

1. WorkshopItems — the Workshop ID, the number at the end of the mod's Steam Workshop page address. The server downloads these items when it starts.
2. Mods — the mod ID, which is the id= line of the mod's mod.info. It is often different from the mod's title and its folder name, and one Workshop item can contain several mods. On Build 42 each mod ID needs a backslash in front.
3. Map — for map mods only, the map folder names, listed before the base map.

WorkshopItems=2169435993;2392709985
Mods=\ModA;\ModB
Map=MyMapFolder;Muldraugh, KY

Separate entries with semicolons and no spaces. List a mod after the mods it depends on. Players do not install anything by hand: the game downloads the server's Workshop mods when they join.

Why mods do not load

• The mod ID is wrong — a title or folder name instead of the id= value, or the Build 42 backslash missing.
• The mod is for the other build. Many mods have separate Build 41 and Build 42 versions; a Build 41-only mod does not load on 42 and can stop the world loading.
• A dependency is missing from WorkshopItems or listed after the mod that needs it.
• The mod updated on the Workshop and the server has the older copy, so players with the new version are refused. Restart the server so it downloads the update. The checkModsNeedUpdate command writes to the log whether an update is waiting.

Settings that cut lag and memory

A Project Zomboid server spends its memory and CPU on loaded areas, zombies and mods. The settings that move the needle:

• Zombie population and respawn. Every zombie is simulated. A High or Insane population with respawn on is the most expensive world you can build; Normal without respawn is far lighter.
• The mod list. Big map, vehicle and overhaul mods cost memory even when nobody uses them. Remove what your group does not play with.
• MaxPlayers that matches reality. Players spread across the map each keep their surroundings loaded. Thirty players in thirty towns cost far more than thirty players in one base.
• PauseEmpty=true stops the clock when nobody is on, so an empty server is not simulating a world nobody sees.
• A scheduled restart once a day keeps a long-running world responsive.

Settings only go so far: if the server keeps running out of memory, it needs more. Our RAM guidance has the numbers per group size.

Changing settings on a HytHost server

On HytHost, settings are split between two places in your GamePanel:

• The Startup tab holds max players, server name, server password, public listing, PvP, Workshop items and mod IDs. The server writes these into servertest.ini every time it starts, so change them here — an edit to those lines in the file is replaced at the next start.
• The file manager (or sFTP) holds everything else: the rest of servertest.ini and servertest_SandboxVars.lua, in Zomboid/Server/. Stop the server, edit, save, start it again.

Take a manual backup from the Backups tab before a big change, on top of the automatic ones every plan includes. For long-running modded worlds, West Point (12 GB) leaves room for map and vehicle packs; Project Zomboid hosting has every size, and Custom servers go up to 32 GB.

Setting up for the first time? Start with how to host a Project Zomboid server.