Modding Mayhem: Add Steam Workshop Mods to Your Project Zomboid Server (B41 & B42)

Yes – you can deck out your Project Zomboid server with Steam Workshop mods in just a few steps! Here's the short version: subscribe to mods on Steam, enable them on your server (via config file or host menu), and restart. Both the host and players will automatically download the mods when joining. Need the nitty-gritty? Jump to the Quick-Start Guide for a speedy rundown, or read on for a detailed toolbox on modding Build 41 and Build 42 servers (co-op and dedicated). Let's turn your apocalypse into a modded madhouse!

Quick-Start Guide to Adding Mods (TL;DR)

Why Mod Your Project Zomboid Server?

Project Zomboid is an amazing sandbox on its own, but mods take it to the next level. From quality-of-life tweaks to full content overhauls, Steam Workshop mods let you tailor the apocalypse to your liking. Want authentic 90s cars, new weapons, or expanded crafting? Mods have you covered. Running a server with mods can rejuvenate gameplay and keep your group engaged long-term.

(Throughout this guide, we'll use examples from Build 41, and highlight differences in Build 42 – the newest version that brings some changes to modding.)

Setting Up Mods in Co-op Host (Peer-to-Peer)

So you're hosting a game via "Host" in Project Zomboid's menu for some friends – easy and quick. But when you start the server, your mods didn't load, or your friends can't see the modded items. Sound familiar? Let's fix that.

Enabling Mods in the Host Menu

When using the in-game hosting feature, Project Zomboid provides a GUI to configure mods (and other settings) for your server. It's crucial to enable mods in two places:

• Mods Tab: This lists the Mod names (Mod IDs) of mods you've subscribed to. Enabling a mod here tells the game to load it.
• Steam Workshop Tab: This tab is where you specify which Workshop items the server should download. Each entry corresponds to a Workshop ID number for a mod.

How to do it:

1. On the Host settings screen, click Steam Workshop on the left panel. Use the dropdown or "Add" button to add each mod's Workshop ID. If you've subscribed to mods, they should be listed by name – select each mod you want. They'll appear in a list with their numeric ID.
2. Now click Mods on the left panel. You should see the names of the mods (Mod IDs). Check the box next to each mod you want to enable on the server. (These correspond to the same mods you added in Steam Workshop tab.)
3. Double-check that every mod you want is present and checked in both lists. For example, to add "Hydrocraft" mod, ensure it's added in Steam Workshop (with its Workshop ID) and ticked in Mods tab as "Hydrocraft".
4. Start the server as usual (click Start or Host).

If done correctly, the server will launch and load those mods. The first time, it may take a moment to download the mod files if you (the host) haven't used them in single-player. The next section explains how that works.

WorkshopItems=2561774086;2286126274
Mods=Hydrocraft;FuelAPI

(The above is just an example: two mods added by their IDs.)

How Clients Download Mods (Syncing with Players)

One great aspect of using Workshop mods is that clients will auto-sync mods when joining a server. Here's what happens:

• When your friend attempts to join your hosted game, the server checks their mods. If they are missing a mod or have the wrong version, the server will notify them. The client will see a popup like: "The server requires the following Workshop items: [Mod Names]. Subscribe and download them now?".
• The player should click Yes/Subscribe. The game (via Steam) will then download those mods automatically. This might kick them back to the menu while downloading. (They may need to wait a minute or two for Steam to finish the download; the process is usually automatic.)
• Once the mods are downloaded, the player can rejoin the server. No additional manual steps needed – the game will load the new mods and connect.

This system means you don't have to send your friends mod files or URLs. As long as the server is correctly advertising the mods (which the Host menu did by populating Workshop IDs), Steam takes care of syncing them. It's pretty seamless when it works.

Troubleshooting Co-op Mod Issues

Even with the above steps, a few things can go wrong in co-op modding. Here's a quick checklist and fixes:

• Mods still not appearing in-game: After starting the server, if you don't see mod content, stop the server and double-check the Host settings. It's easy to forget a tab. Ensure the mod is in both lists and try again. Also verify that you (the host) actually see the mods enabled in your main menu's Mods screen (on the PZ main menu) – if not, the game may not have downloaded them properly for you.
• Friends can't join due to mods mismatch: Ensure everyone, including host, is on the same game version (Build 41 vs 41.78, etc., or the same beta branch if using one). Mismatched game versions can falsely flag mods. If the game versions are same, then ensure every listed mod is actually downloaded for the client. Sometimes unsubscribing then re-subscribing to a problematic mod can grab the correct version.
• "Workshop item not found" error: This can occur if a mod was removed from Workshop or set to hidden. If you see this, identify which mod ID is causing it (the error usually lists an ID). You might need to remove that mod from your server list (it's no longer available). Alternatively, find if the mod has a replacement or updated version.
• Game won't start after enabling a mod (host side): If the host's game is crashing on startup after enabling a mod in the host settings, one of the mods might be corrupt or conflict with another. Disable all mods, then add them back one by one to find the culprit. It's rare in Build 41 for a mod to outright crash on load, but it can happen with outdated mods. If found, exclude that mod or seek an updated version.
• Co-op performance issues: Not directly a "mods not working" issue, but be aware that some large mods (huge map mods or overhauls like Hydrocraft) can increase memory/CPU usage for the host. If the host machine is struggling, it might manifest as lag or even mod loading failures. The solution might be to upgrade the host hardware or move to a dedicated server for those heavy mods.

By now, you should have a co-op server running mods successfully. Next, we'll tackle dedicated servers, which require a bit more manual setup but offer more control and persistence.

Installing Mods on a Dedicated Server (Windows & Linux)

Dedicated servers are the way to go for a persistent world or for hosting when the game isn't running on your PC. They run separately from the game client. This means we can't just tick boxes in a GUI; instead, we configure mods through files or commands. Don't worry – it's straightforward once you know where to look.

Whether you're on Windows or Linux, the key is to update the server's configuration so it knows which mods to download and enable. Project Zomboid's dedicated server has built-in Steam Workshop support, so it can fetch mods on startup if configured correctly.

Windows Dedicated Server: Adding Mods Step-by-Step

Prerequisite: You should have the Project Zomboid Dedicated Server installed (via Steam or SteamCMD) and running at least once. If not, set that up first (it creates the default server files). Let's call our server "servertest" (the default).

1. Locate the Server INI File: Navigate to your PZ server files. If installed via Steam on Windows, it's typically in:
   C:\Users\<YourUser>\Zomboid\Server\servertest.ini This is the config file with all server settings. Open servertest.ini with a text editor (Notepad works, though something like Notepad++ is nicer).
   (If you used a custom server name, find <servername>.ini instead of servertest.ini.)
2. Find Workshop and Mods lines: Scroll or search (Ctrl+F) for the lines beginning with WorkshopItems= and Mods=. By default they might be blank or commented out. For example:

   WorkshopItems=
   Mods=

   If they're missing entirely, ensure you opened the correct file, or add the lines under the [MAIN] section.
3. Gather the Mod IDs: For each mod you want, you need two identifiers:
   • The Workshop ID (a number, e.g. 2169435993)
   • The Mod ID (a string, e.g. WeaponExpansion)
   How to get these: Open the mod's Steam Workshop page in your browser. Scroll to the bottom of the description; most mod authors list "Workshop ID" and "Mod ID" there. For example, on an item page you might see: "Workshop ID: 2818847163 | Mod ID: 80kz1000". (If it's not clearly listed, it might be in a pinned comment or the URL. The number in the page URL after ?id= is the Workshop ID.)

   Write down each pair of IDs. For illustration: let's say we want Tsar's Common Library mod (needed by many vehicle mods) and '80 Kz1000 Police Bike' mod. From their pages:

   • Workshop ID 2392709985, Mod ID tsarslib
   • Workshop ID 2818847163, Mod ID 80kz1000
4. Edit the lines: In servertest.ini, input the IDs. WorkshopItems= gets the numeric Workshop IDs, separated by a semicolon ; with no spaces. Mods= gets the textual Mod IDs, also semicolon-separated. For our example:

   WorkshopItems=2392709985;2818847163
   Mods=tsarslib;80kz1000

   It's critical these line up in corresponding order (though the game usually matches by name regardless of order, it's good practice to have them in parallel). Each Workshop ID should have its Mod ID listed; otherwise the server won't know to actually load that mod after downloading.

   Editing the server .ini config to add mods. The WorkshopItems line lists the Steam Workshop IDs for mods to download, and the Mods line lists the corresponding Mod IDs (from mod info). Here we've added two mods as an example.

5. Save and Close the file. Double-check there are no typos. (A common mistake is leaving a trailing semicolon at the end of the list – it's harmless if you do, the server will ignore a blank entry, but best to keep it clean.)
6. Start the Server: Launch your dedicated server (e.g., run the StartServer64.bat on Windows or launch via Steam). Watch the console output. You should see it contact Steam and begin downloading the mods you listed. It will look something like:

   QUERYING WORKSHOP ITEMS...
   Downloading item 2392709985 ... done
   Downloading item 2818847163 ... done

   Then it loads those mods (look for lines like "Loaded library tsarslib" etc.). If you see errors here (e.g., "Failed to download Workshop item"), ensure the Workshop ID is correct and that Steam isn't having issues. Occasionally, Steam's workshop can be slow or down; the server might try again automatically.
7. Done! The server now has the mods. Clients can join and will be prompted to download these mods (just like in co-op). The mods will be active on the server world – new items, mechanics or maps introduced by them should now function.

Example config snippet (after adding mods):

# Steam Workshop Mods to Install (IDs)
WorkshopItems=2392709985;2818847163

# Mods to Enable (Mod folder names)
Mods=tsarslib;80kz1000

# (other settings like Map, etc. below)
Map=Muldraugh, KY
...

(Notice we put Tsar's Library first in both lists, then the Bike mod second. Tsar's Library is a required dependency for the bike mod, so it's listed as a separate mod entry.)

Linux Dedicated Server: Adding Mods (SteamCMD or Manual)

Running a PZ server on Linux is quite common for dedicated hosts. The process is similar, but since there's no Steam GUI, you rely on SteamCMD or the server's own workshop integration.

Option 1: Let the Server Download Mods (Steam Workshop Integration)

Project Zomboid's server can download mods on Linux just like on Windows, as long as it can reach Steam. You will still edit the ServerName.ini file exactly as above (with WorkshopItems and Mods lines). The only catch: If you run the server with the -nosteam flag (i.e., without Steam integration), it cannot download from Workshop. So ensure your start script is not using -nosteam. The default behavior (if you just run the ProjectZomboidServer64 script without -nosteam) is to use Steam and allow workshop downloads.

After editing the ini, start the server. The first start might output something like "Connecting to Steam" followed by the downloading messages. On Linux, the workshop content typically goes into the Steam/steamapps/workshop directory under the user that runs the server. If your server fails to download (for example, if you see errors about "not logged in"), you might need to use SteamCMD with a login.

Option 2: Using SteamCMD to Pre-download Mods

In some setups, you might prefer to fetch mods via SteamCMD manually. For instance, if your server is running in a container or you want to pre-cache mods.

Here's how to use SteamCMD for PZ mods:

1. Install SteamCMD on your Linux server if not already installed.
2. For each mod's Workshop ID, run:

   steamcmd +login anonymous +workshop_download_item 108600 <WorkshopID> +quit

   Replace <WorkshopID> with the numeric ID (e.g., 2818847163). The 108600 is PZ's game ID on Steam. This command logs in anonymously and downloads the item to ~/.steam/steamcmd/workshop/content/108600/<WorkshopID>. (If you have a Steam account and prefer, you can login with your credentials instead of anonymous; usually not necessary for public mods.)
3. Repeat for all mods or write a small script to loop through a list of IDs.
4. Once downloaded, you need to move or symlink these mod files to where the PZ server expects them. The dedicated server looks in its installation's steamapps/workshop/content/108600 directory by default (for Steam integration) or sometimes the Zomboid/Workshop folder in your home directory (for the user's local files). To be sure, you can create a directory structure the same as on Windows. One approach:
   • Copy the folder <WorkshopID> from steamcmd/workshop/content/108600/ to the PZ server installation under media/workshop/ or into the user's Zomboid/Workshop folder. Recent versions should recognize them if placed in the correct spot.
   • Alternative: Launch the server normally after editing the ini – it might actually detect the presence of those already-downloaded mods and just use them (since SteamCMD downloads are in the same path it would use).
5. Edit servertest.ini as described earlier (WorkshopItems and Mods lines). Even if you manually downloaded the files, you still need to list them in the config for the server to load them. If you've placed files correctly, the server may skip downloading (it might say already up-to-date) and just load them.
6. Start the server. Verify it finds and loads the mods.

Confirming Mods Loaded on Dedicated Server

Regardless of OS, after the server is up, you can confirm mods loaded by either:

• Checking the console/log: You'll usually see each mod name mentioned. For example, lines like MOD: Mod "Tsar's Common Library" has been loaded or similar. The log file logs/console.txt will contain these.
• In-game, join the server as admin and use /mods command in chat. This command (if available) lists active mods on the server. (If not, simply verify that mod content is present – e.g., craft a mod item or check admin panel for mod-added items).
• The server's UI (if using the Terminal UI on Windows) might show an "Mods:" field listing active mods as well.

If something didn't load, double-check spelling and punctuation in servertest.ini. A single typo in Mod ID will cause that mod not to load, even if downloaded. It's forgiving about order and whitespace but not about exact IDs.

Client Considerations for Dedicated Servers

From the player side, joining a dedicated server with mods is the same experience as joining a co-op host:

• If the player has the mod already (subscribed in Steam), the game will compare versions. If up-to-date, they join seamlessly.
• If the player doesn't have the mod, they'll get the subscribe prompt. They should accept, let it download, and rejoin.
• If a mod is large, they might time out on first join if download is slow. It can help for server owners to share their mod list (perhaps via a Steam Workshop Collection) so players can pre-subscribe and download mods beforehand. That way, they connect quickly.
• If using a Steam Workshop Collection, note that the server itself doesn't know what a "collection" is – you still list individual mod IDs in the config. The collection is purely for player convenience (one-click subscribe to all).

We've now covered the heavy lifting of getting mods on both co-op and dedicated servers. Next, let's discuss some version-specific nuances (Build 41 vs Build 42) that can impact your modding experience.

Build 41 vs. Build 42: Modding Differences and Tips

Project Zomboid's Build 41 has been the stable foundation for a long time. Build 42 is the new (currently unstable as of this writing) version that introduces many changes – including how mods are handled. Here's what you need to know if you're venturing into B42:

(Up next: some advanced tips, tools, and scripts to supercharge your modded server management – especially useful for those running many mods or wanting automation.)

Advanced Modding Toolbox: Power-User Tips and Tools

So you've got the basics down – but maybe you're managing a server with dozens of mods, or you want to streamline the update process. This section covers advanced techniques and handy tools that can save you time and headaches.

Managing Large Mod Lists with Mod Manager Mods

Enabling 5 mods is one thing; enabling 50 is quite another. Doing that via a text file or clicking each one in the UI is tedious and error-prone. Enter the "Mod Manager" family of mods.

One standout is Mod Manager: Server by NoctisFalco. It's a client-side mod (for the game UI) that extends the regular mod manager. What does it do? In short, it provides a new interface to organize and apply mods to your server config. Features include search, filters, and the ability to save mod presets specifically for servers. Crucially, it helps ensure that when you select a mod that has required dependency mods, you won't forget to include them – "Now you will never forget to add required mods to your server's config!" as the author says.

Some players even use this mod manager locally to prepare a config for a remote dedicated server: they enable mods in the UI, then copy the generated WorkshopItems and Mods lines from their local servertest.ini to the rented server. This was described in a Reddit thread: use the mod manager to generate the server ini, then "copy this file and upload it… to your dedicated server". It's a clever way to avoid manual errors.

Since Build 42 is introducing an official mod manager, these mods might become less essential on that version – but for Build 41, they are lifesavers for heavy mod users. Even on B42, if the official UI lacks some features, the community mod manager might still be useful.

Using Steam Workshop Collections for Easy Subscribing

While the server can't directly use a Workshop Collection ID to load mods, you can leverage collections to simplify life for your players (and yourself).

What is a Workshop Collection? It's basically a list of mods on Steam Workshop that you curate, which others can subscribe to in one click. If you make a collection for your server, you can include all required mods in it. Then, if a new player wants to join, you just send them the collection link and say "Subscribe to all". They'll get all the mods downloaded in one go (or at least queued), rather than needing to individually accept each mod on join.

For example, say your server uses 30 mods. Without a collection, a new player would join, get 30 separate "subscribe?" prompts, and Steam would download each. It works, but it's slow and can overwhelm or annoy the user. With a collection, they pre-download so when they first join your server, ideally they already have everything.

Automating config from collections: If you have a collection and want to get all the Workshop IDs out of it to paste into your config, tools like PZidgrabber come in handy. With PZidgrabber (a web tool), you paste your collection URL, and it will spit out two lists: one of all Workshop IDs, and one of all Mod IDs (if it can find them) ready to plug into WorkshopItems and Mods. This was recommended in a guide for easier config editing. It's not an official tool, but it's simple and saves time versus clicking through each mod page manually.

Remember that if your collection changes (e.g., you add a new mod), you'll need to update your server .ini as well; the collection itself doesn't magically sync to the server.

Automating Mod Updates (Keeping Server Mods Up-to-date)

One headache servers face is when a mod on Workshop updates, but your server hasn't restarted to grab it. Players then get the dreaded "Workshop item version is different" error until you update. If you have active admins, you can monitor and reboot when needed. But you can also automate this process to an extent.

:loop
@echo Started: %date% %time%
Start "" /wait StartServer64.bat
goto loop

Linux approach: You can achieve similar with a shell script or systemd service that restarts on exit. Or use tools like tmux/screen with a while loop. The principle is the same.

If you prefer not to use a mod to detect updates, you could schedule daily restarts during off-peak hours to catch updates, or monitor the Workshop RSS feeds for your mods. There's also a community tool called PZ Server Governor (and similar scripts) that can check mod timestamps, but that gets pretty fancy.

The combination of Udderly Up To Date + auto-restart script is currently the closest to a fully automated solution and has been reported to work (as of early 2025). Keep in mind, if Build 42 or later introduces official solutions, these might become obsolete or easier.

Handling Mod Conflicts and Load Order

Project Zomboid mods generally play nice together – especially since most mods are additive (they add new items, recipes, etc., rather than overwriting base files). However, there are cases where mods conflict or you need a specific load order:

• Conflicts: Two mods might modify the same game file or system (for example, two different mods both altering how firearms work). In B41, whichever mod is loaded last will override conflicting definitions of the first. The load order by default follows the order in the Mods= line. So you can technically control priority by ordering those mod IDs. If you suspect a conflict, try swapping the order and see if the behavior changes. The better approach is to check if the mod authors have patches or compatibility notes. Sometimes, mod A will say "place this below mod B" if it's designed to overwrite some of B's behavior.
• Enhanced Load Order UI: The same creator of Mod Manager made "Mod Manager: Enhanced Load Order", a mod that helps visualize and change mod load order with drag-and-drop. This is more of a convenience for client side (and useful if you have many mods that could conflict). It's not strictly necessary for servers unless you're debugging an issue.
• Required/Dependent Mods: Many mods depend on others (common libraries). We mentioned Tsar's Library, there's also FuelAPI, ARKs mod pack dependencies, etc. The server must have all required mods listed, or it will complain "requires mod X" and refuse to load the dependent. The console log actually will say something like "Mod Y requires X, which is missing". Always include all required mods as listed on the Workshop page (usually mod authors list "Requires: …" at top or bottom). If you use the Mod Manager mod or the workshop UI, they often auto-include dependencies when you select a mod, which is convenient.
• Too Many Mods? There isn't a hard number limit that's publicly stated, but running dozens (50+) mods can increase the chance of issues. Not just conflicts, but performance: each mod's code runs and some might eat CPU. Monitor your server's performance; if ticks lag or memory use balloons, consider trimming mods or checking if a particular mod is the culprit via removal testing.

Mid-Game Mod Changes (Adding/Removing Mods in an Existing World)

Sometimes you want to introduce a new mod to spice up an ongoing server, or remove one that's problematic. This can be done, but proceed with caution:

• Adding a Mod: For most mods, adding them on the fly is okay. Example: adding a new vehicle mod will simply start spawning those vehicles (in areas that spawn after addition). Adding a new items mod – those items will start appearing in loot going forward. The things that won't happen are retroactive insertion into already-looted containers or already-explored map chunks. So, you might have to venture to unexplored areas to find the new stuff, or respawn loot via server settings if desired. Important: when you add the mod to the server config and restart, all players must also get the mod (they'll be prompted on join as usual). Ensure everyone knows to download it. If players use collections or a mod loader like we discussed, update those accordingly.
• Removing a Mod: This is trickier. If the mod added any persistent data (items, objects, traits), removing it can cause issues or errors when loading saved areas that contain those things. For instance, if you remove a mod that added a new type of container, any that were placed in the world might vanish or cause errors. The game might throw red errors in console about missing scripts. The safest way to remove a mod is when starting a fresh world. If you must remove it mid-save, try to remove all instances of its content in-game first (e.g., have players destroy or drop-and-burn items from that mod), then remove it and hope for minimal issues. Always backup your save (Zomboid/Saves/Multiplayer/<server> folder) before removing a mod, so you can rollback if needed.
• Mod Updates Changing Gameplay: A mod might update and substantially alter things (like rebalancing items). Communicate with your players – sometimes an update can feel like adding/removing a mod in terms of effect. For example, a farming mod might suddenly use different seeds post-update. Usually not breaking, but can confuse players.

If you plan major mod list changes, doing them between server "seasons" or wipes is ideal. For a long-term server, gradually adding mods is fine (we all love new toys), but frequent changes can make the experience inconsistent. Also note, if you heavily alter the mod list, your server's checksum (the fingerprint of mod configuration) changes; players might have to re-download some things on join (the game handles it but just an FYI).

Realistic Example: Putting It All Together

Let's illustrate with a scenario: You run a dedicated server "ZombieLand" on Build 41. You want a host of mods:

• Maps: Fort Redstone, Bedford Falls
• Gameplay: ORGM (Gun mod), Hydrocraft (big items mod), Advanced Trajectory, Autotsar Tuning
• Fun: Superb Survivors (NPCs), and some admin tools mod.

1. Step 1: Subscribe to all on your Steam account. Start the server once (without mods) to generate files.
2. Step 2: Edit servertest.ini: list all Workshop IDs in one long WorkshopItems= line, and all Mod IDs in Mods= line. Double-check each. For example, Hydrocraft's Workshop ID is ---, Mod ID "Hydrocraft"; ORGM's ID is ---, Mod "ORGM"; etc. (Hydrocraft and ORGM both have dependencies – make sure to include any libraries they need.)
3. Step 3: Restart server. It downloads ~2GB of mods (Hydrocraft is big!). It loads them. Some messages about missing HCBattery item distribution pop up – maybe a minor issue, but it runs.
4. Step 4: Players join, get 10 prompts for mods – you realize you should have used a collection! You quickly create a Workshop Collection "ZombieLand Mod Pack" and share the link in your Discord. New players use that instead of clicking yes ten times.
5. Step 5: A week later, a patch updates Autotsar Tuning mod. Players see mismatch. You hadn't installed any auto-update system, so you manually restart the server that evening. It downloads the new Autotsar version and everything is well. To avoid mid-day disruptions, you decide to install the Udderly UpToDate mod and set up the restart script for next time.
6. Step 6: Some mods (like Superb Survivors) occasionally glitch – an NPC mod might throw errors if combined with others. You watch the logs and community forums. One conflict is found: Superb Survivors conflicts with an AI tweak mod you also added. You remove the AI tweak mod (delete its IDs from .ini, restart). Some leftover items from it remain in players' inventories but appear as "Unknown Item" – they discard them.

Through all this, you've seen how managing mods can be a bit of work, but the enriched gameplay is worth it. By following best practices and using available tools, you kept the chaos manageable.

Finally, let's wrap up with a short recap and additional resources for your modding journey.

Action Steps Recap

Modding your Project Zomboid server might seem daunting, but it boils down to a few key actions:

By following these steps and tips, you'll create a robust, customized Project Zomboid experience. You've effectively turned your server into your own zombie survival RPG, tailored exactly how you and your friends like it. Just like scavenging for the best gear in Knox County, you've scavenged knowledge from this guide to survive the sometimes brutal world of mod management – congrats, survivor!

FAQ

FAQ: