The Indie Stone posted an announcement on October 21, 2026, addressing Project Zomboid Java mods and the studio’s official modding support policy.
What Changed
The developers opened by thanking the modding community and noting a recent surge in creativity, with some mods changing the game at a fundamental level. They attributed this to Java, the core coding language of Project Zomboid, and to Java-based loaders and frameworks.
The announcement then turned to risks. The Indie Stone advised players to download mods responsibly, only from sources and authors they trust. They noted that Java mods typically require manual installation, external downloads, special loaders, or steps beyond clicking Subscribe on the Steam Workshop.
Because Java mods can change the game’s code directly, they can potentially create security vulnerabilities. The developers contrasted this with Lua mods, which stay within Project Zomboid’s code: a Lua mod repaints a house and adds wallpaper, while a Java mod builds a new house nearby, possibly with an unseen back door.
The Indie Stone stressed that not all Java mods are malicious, but they require a different level of trust. Installing one means allowing third-party code to run on the player’s machine.
The developers strongly encouraged open source mods or reproducible builds for transparency, while cautioning that neither guarantees safety. They also recommended that Java modders themselves provide open source or reproducible builds.
Steam Workshop has systems to flag and report mods, and popular mods have many installs, but that is not a guarantee of safety. For mods from other sources, players should check whether source code is public and files can be independently verified.
The announcement then stated the studio’s official support policy: The Indie Stone officially supports Lua-based modding for Project Zomboid. Java-based mods, including third-party loaders, frameworks, and modifications that alter the game’s underlying implementation, are not officially supported.
Project Zomboid’s internal implementation is not a supported modding interface. Java-based mods rely on internal code that changes as the game develops, so new updates will fundamentally break them without warning.
The studio cannot provide technical support for Java-based mods, resolve compatibility problems, or dedicate development resources to them. Bug reports are only investigated when the bug is found in an un-modded game save, and must be reproducible without mods to be considered.
The policy is not a judgment on individual mods or their creators, but a necessity for testing, supporting, and maintaining Project Zomboid.
You are not simply installing new game content; you are allowing third-party code to run on your machine.
Who It Affects
Players who use Java-based mods or consider installing them are affected by the security guidance and the lack of official support. Lua mod users are not affected by the Java-specific risks, but all mod users are subject to the bug report requirement that issues be reproducible without mods.
For every Project Zomboid announcement, check the Project Zomboid update tracker.
