Project Zomboid: setting up Java mods with ZombieBuddy

ZombieBuddy loads Java mods for Project Zomboid Build 42. Mods such as Project Viewpoint require it. On your server, you set up ZombieBuddy yourself and decide for each Java mod whether it is loaded.

Requirements

• Flex M or higher: Workshop mods and file uploads are available from Flex M.
• Project Zomboid Build 42.
• The file ZombieBuddy.jar from the GitHub page of the project (zed-0xff/ZombieBuddy).

Step by step

1. Download ZombieBuddy.jar from the GitHub page of the project.
2. In the customer portal, open your server, then the file manager in the card „Dateien“ (Files), and upload the file to the top-level folder. Alternatively via SFTP.
3. In the „Einstellungen“ (Settings) card, enter the following in the „Java-Startparameter“ (Java start parameters) field: -javaagent:ZombieBuddy.jar=policy=deny-new. The entry is saved automatically. If the file is not in the server's data folder, the customer portal rejects the entry.
4. Enter the mods as described in Setting up Project Zomboid mods: the Workshop ID 3619862853 for ZombieBuddy and the mods you want, for example Project Viewpoint (3809306528) and Surface Fix (3814398576). The Mod IDs are ZombieBuddy, Viewpoint and ViewpointSurface. Start the server.
5. Open the card „Java-Mods“ (Java mods) with „Java-Mods anzeigen“ (Show Java mods). New Java mods are listed there as „neu“ (new) with „letzter Start: blockiert“ (last start: blocked), together with Mod ID, Workshop ID, file, date, SHA-256 checksum and signature (validly signed or unsigned).
6. For each mod, select „Laden“ (Load) or „Nicht laden“ (Do not load) and restart the server. The selection applies from the next start.

After a mod update

If an update changes the file of a Java mod, the list shows „geändert, nicht freigegeben“ (changed, not approved). The new file stays blocked until you approve it again. This way you decide yourself when an update is loaded.

Notes

• Without the Java startup parameter, the card „Java-Mods“ shows „ZombieBuddy nicht aktiv“ (ZombieBuddy not active).
• Project Viewpoint is tied to one game version, currently 42.21. After an update of Project Zomboid, the mod only loads again once its author publishes a matching version.
• Java mods run their own program code on the server. The signature in the list shows whether the file is signed.
• Tested on October 25, 2026 with Build 42.21, ZombieBuddy 2.3.4, Project Viewpoint and Surface Fix on Flex L.

Frequently asked questions

Why does my Java mod not load?

Check in the card „Java-Mods“ whether the mod is set to „Laden“ or shows „geändert, nicht freigegeben“ after an update. The selection only applies after a server restart.

From which tier are Java mods available?

From Flex M, because Workshop mods and file uploads are only available from that tier.

See also: Setting up Project Zomboid mods Custom Java startup parameters Project Zomboid: sandbox settings

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