How to add mods to a Project Zomboid server

Project Zomboid mods come from the Steam Workshop. The server downloads them itself from Steam, and so does each player’s game when they join. In the Mods tab you can search the Workshop and install a mod with one tap, and we keep the server’s two mod lines in step for you.

How Project Zomboid mods work

Every mod needs two entries in Zomboid/Server/wilderack.ini:

One Workshop item can hold several mods, each with its own mod ID. Some are options you pick between, so you don’t always want them all. If a mod adds a map, its map folder also goes in the Map= line.

If the two lines get out of step, the mod won’t load. That’s the most common mod problem on Project Zomboid servers, and the Mods tab is built to avoid it.

Install a mod from the Mods tab

1. Open Mods in the panel and search for the mod by name.
2. Check that it supports your server’s build. The search shows which mods match.
3. Install it. If the Workshop item holds several mods, pick the mod IDs you want. Required mods (often called libraries or frameworks) are added too.
4. We take a backup first, then add the item number to WorkshopItems= and the mod IDs to Mods=.
5. Restart the server to turn the mod on. A sleeping server picks it up the next time it starts.

Add a mod by hand

1. Open the mod’s Steam Workshop page. The number after ?id= in the link is the Workshop ID.
2. Find the mod ID. Most authors list it on the Workshop page as “Mod ID”. It’s also the id= line in the mod’s mod.info file.
3. Stop the server, or be ready to restart it.
4. In Files, open Zomboid/Server/wilderack.ini.
5. Add the Workshop ID to WorkshopItems= and the mod ID to Mods=. Separate several with ;.
6. Save and restart.

On Build 42, write each mod ID with a backslash in front. That’s how the game itself writes them:

WorkshopItems=1111111111;2222222222
Mods=\ExampleLibrary;\ExampleMod

On Build 41, leave the backslash out:

WorkshopItems=1111111111;2222222222
Mods=ExampleLibrary;ExampleMod

For a map mod, add its map folder in front of the main map, like Map=ExampleTown;Muldraugh, KY.

Load order

Mods load in the order of the Mods= line. Put required mods and libraries first, then the mods that use them. If two mods change the same thing, the one later in the list usually wins. The Mods tab puts required mods first for you.

What your friends need

Nothing extra. When a friend joins, their game downloads every Workshop mod the server uses. The first join takes longer while that happens. They do need the same build of the game as the server.

Updates and version matching

Project Zomboid’s server downloads the newest version of each Workshop item every time it starts. Players’ games update their mods through Steam as soon as an author publishes a change.

So when an author updates a mod while your server is running, players can’t join until the server restarts. They see “Workshop item version is different than server’s”. A restart fixes it. A daily restart in Schedules keeps this from happening often. See the error guide.

The Mods tab shows when a mod has an update, with its changes, so you know what changed.

Build 42 and mods

Build 42 changed how mods are built, so many Build 41 mods don’t work on it. Before you add a mod to a Build 42 server, check the Workshop page says it supports Build 42. If you depend on mods that are Build 41 only, see Build 41 vs Build 42.

The Indie Stone supports mods written in Lua, which is what almost every Workshop mod is. Mods written in Java change the game’s own code. The developers don’t support them, and they usually need special loaders installed by hand. We don’t install Java mods.

Removing a mod

Remove it in Mods, or delete it from both Mods= and WorkshopItems= and restart. Items, vehicles and buildings that came from the mod can vanish from your world. We take a backup before every mod change, so you can go back if something breaks.