ZombieBuddy
A framework that enables advanced Java mods for Project Zomboid.
What it does:
ZombieBuddy is required by some mods to work. If a mod tells you to install ZombieBuddy, follow the instructions below.
Step 1: Subscribe to ZombieBuddy on Steam Workshop
Step 2: Installation is required ONLY ONCE for ZombieBuddy itself.
🪟 Windows:
Option A: Automated Installer (Recommended)
- Download the latest ZombieBuddyInstaller.exe from GitHub Releases[github.com]
- Run the installer and choose Install or update ZombieBuddy.
- Choose what launch mode to patch:
- Both (recommended): patches Normal Launch and Alternate Launch.
- Normal Launch: then choose ProjectZomboid64.json, Steam launch options, or both.
- Alternate Launch: patches ProjectZomboid64.bat.
- The installer shows every system change first and asks for confirmation before applying it.
- If Steam launch options need to be changed, the installer will ask you to close Steam at that point.
- The same installer can also uninstall ZombieBuddy later: run it again and choose Uninstall ZombieBuddy.
Option B: Manual Installation
- Copy ZombieBuddy.jar and zbNative.dll from:
C:Program Files (x86)Steamsteamappsworkshopcontent1086003619862853modsZombieBuddylibs
to your Project Zomboid folder:
C:Program Files (x86)SteamsteamappscommonProjectZomboid - Open Project Zomboid’s launch options in Steam
- Add this launch option:
-agentlib:zbNative —
- ⚠️ IMPORTANT: The — at the end is mandatory – do not omit it!
- If you use the game’s Alternate Launch option on Windows, set the ProjectZomboid64.bat _JAVA_OPTIONS line to:
SET _JAVA_OPTIONS=-agentlib:zbNative
🍎 macOS / 🐧 Linux:
- Copy ZombieBuddy.jar from the mod’s libs/ directory to:
- macOS: ~/Library/Application Support/Steam/steamapps/common/ProjectZomboid/Project Zomboid.app/Contents/Java/
- Linux: ~/.steam/steam/steamapps/common/ProjectZomboid/projectzomboid/
- Open Project Zomboid’s launch options in Steam
- Add this JVM argument: -javaagent:ZombieBuddy.jar —
- ⚠️ IMPORTANT: The — at the end is mandatory – do not omit it!
Step 3: After this setup, all mods that require ZombieBuddy will work automatically!
- Disable the agent first: Open Project Zomboid → Properties → clear the Launch Options line
- Delete zbNative.dll and ZombieBuddy.jar from your Project Zomboid install directory
- Unsubscribe from ZombieBuddy on Steam
Java mods enabled through ZombieBuddy have unrestricted access to your system. Only install mods from sources you trust.
No jar will sneak in. Whenever a Java mod ships a new or updated JAR, ZombieBuddy shows a native dialog with the mod id, file path, last-modified date, and SHA-256 fingerprint. Nothing is loaded until you click Yes. You can choose to remember the decision (per-mod, per-hash) or keep it session-only. Persisted allow/deny choices are written to JSON (mod id → { sha256 → true|false }) at:
- Windows: %USERPROFILE%.zombie_buddymod_approvals.json
- macOS / Linux: ~/.zombie_buddy/mod_approvals.json
If a previously-approved JAR changes on disk (hash mismatch), you will be prompted again.
Tip: hold Shift during game load to force the approval dialog to appear, even for previously approved Java mods.
Controls what happens when an unknown/changed JAR is seen. Pass as a policy=… argument:
- prompt (default) – ask me each time via a native dialog.
- deny-new – silently skip any JAR that isn’t already approved.
- allow-all – load every JAR without prompting. Not recommended.
Examples (block form, these go into Steam launch options):
- Is it a virus?
No. - How to start game in debug mode?
-agentlib:zbNative — -debug OR -javaagent:ZombieBuddy.jar — -debug - Do I need to repeat manual installation after I upgrade/downgrade/validate game?
No, if you use the default launcher and have agentlib in Steam launch options.
Yes, if ZombieBuddy stops loading. - Works on MP?
Yes. - Save compatibility?
Safe to add or remove on existing saves. - I clicked the wrong button in the approval dialog. How do I reset it?
Open mod_approvals.json (path above), under ‘mods’ find your mod id, then remove or edit the SHA-256 key you want to reset (or change true/false), save, and restart. - Can I see which Java mods were loaded or blocked?
Yes – install Zed’s Better ModList and the status is shown next to each JAR path in the mod list. - Supported game versions?
B41, B42.12-B42.17 - Can I hide ZB watermark?
Yes, in ModOptions. During game boot it is always visible. - WHY ALL LINKS ARE REMOVED FROM THIS PAGE AND COMMENTS DISABLED???!!!
Steam does that while it checks a newly uploaded mod version for viruses, I suppose. Everything should return to normal in 10..30 minutes, depending on how busy their system is.
GitHub Repository[github.com]
If you find ZombieBuddy useful, consider supporting its development:
[ko-fi.com]
Workshop ID: 3619862853
Mod ID: ZombieBuddy
Revisions:
Old revisions of this mod are available below. Click the link to download.