Crimes Against the JVM
Crimes Against the JVM is a Fabric client-side mod for 1.21.1 that lets a player run JVM bytecode from in-game books.
What it does
Books the author wrote can carry bytecode that executes on the player's own client, so the effect depends on what each book contains. Only the client needs the mod; a server runs without it, and players join it without installing anything. The mod is listed as compatible with Fabric API-based setups that bridge other loaders. The code is open source under the GNU General Public License v3.0 only, with 1.0.5 for 1.21.1 as the latest Fabric file, dated 2024-11-07.
Key features
Bytecode books
Books can hold JVM bytecode that runs when the book is opened, letting the author define custom behavior.
Offhand activation
A book is triggered by holding it in the offhand and pressing a key, which is unbound by default.
Client-only execution
Code in these books runs only on the client, so it cannot change the server.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
How it compares
Crash Command is a Fabric mod for 1.19 – 1.21.8 that runs on the client or the server, with the server optional, under the MIT License. Command Books is a Fabric mod for 1.19.4 – 1.21.11 where the server is required and the client optional, also under the MIT License. Short Players is a Fabric client-side only mod for 1.20.1 – 1.21.10 and is not open source.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Crimes Against the JVM | Fabric | 1.21.1 | Client-side only | 2024-11-07 |
| Crash Command | Fabric | 1.19 – 1.21.8 | Client or server, optional | 2025-06-28 |
| Command Books | Fabric | 1.19.4 – 1.21.11 | Server required, client optional | 2025-12-20 |
| Short Players | Fabric | 1.20.1 – 1.21.10 | Client-side only | 2025-11-16 |
Questions
Does Crimes Against the JVM need to be on the server?
Which game version does Crimes Against the JVM support?
In the catalog
Crimes Against the JVM is one of 7,555 Cursed mods on ModsFinder, and one of 4,235 Cursed mods for Fabric. 32,366 mods support Minecraft 1.21.1.
More from Fractalflower Modding
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What the author says
Execute arbitrary JVM bytecode from books you wrote (Has to be your PlayerEntity as the author for security reasons) - just hold it in your offhand and press the key (Unbound by default, also for security reasons.) Will not run on servers, for hopefully obvious reasons.
Official listing
- Modrinth page
- modrinth.com/mod/crimes-against-the-jvm
- Owner
- Fractalflower Modding
- Published
- 2024-11-04
- Updated on Modrinth
- 2024-11-07
- Facts verified
- 2026-10-15