Axion

Axion is an open-source Minecraft building toolkit. The Fabric mod provides hotbar-driven editing tools and live in-world previews; the matching Paper plugin applies and validates those edits on multiplayer servers.

What Axion Does

• Move, clone, stack, smear, erase, extrude, and mirror terrain directly from the hotbar.
• Preview edits in-world before confirming them, including large GPU-rendered selections.
• Select organic regions with Magic Select, masks, templates, and a searchable block picker.
• Use symmetry, saved hotbars, replace mode, infinite reach, no-clip, and other creative building utilities.
• Undo and redo edits locally or through the companion Paper plugin.

Axion is designed for creative building. Singleplayer edits can run locally. On Paper servers, builders install the Fabric mod and the server runs the matching Axion Paper jar so edits remain authoritative and policy-aware.

Downloads

Download the latest Fabric and Paper jars from:

https://castled.codes/axion/downloads

Choose the jar whose filename matches the Minecraft version range you run. Keep the Fabric mod and Paper plugin on the same Axion version.

Supported Versions

Component	Supported Minecraft versions
Fabric client mod	1.21 - 1.21.11, 26.1 - 26.1.2
Paper plugin	1.21 - 1.21.11, 26.1 - 26.1.2
Fabric dedicated server	1.21.11

Release artifacts are grouped into seven compatibility ranges:

• 1.21 - 1.21.1
• 1.21.2 - 1.21.3
• 1.21.4
• 1.21.5
• 1.21.6 - 1.21.8
• 1.21.9 - 1.21.11
• 26.1 - 26.1.2

Installation

For singleplayer, install the Axion Fabric jar together with Fabric API and Fabric Language Kotlin.

For a Paper server:

1. Install the matching Axion Fabric jar on each builder's client.
2. Install the matching Axion Paper jar in the server's plugins directory.
3. Restart the server and grant the required Axion permissions.

See PLUGIN-README.md and the wiki for server configuration and permissions.

Contributing

Contributions and focused bug reports are welcome. A full release-range build is:

./build-axion.sh all

Launch a development client for a specific supported version with:

./run-axion.sh 1.21.3
./run-axion.sh 1.21.11
./run-axion.sh 26.1

Before opening a pull request, test the affected Minecraft ranges and describe the versions you verified. See CONTRIBUTING.md for the project layout, compatibility rules, and server test commands.

Project Links

• Downloads: https://castled.codes/axion/dl
• Issues: https://github.com/castledking/Axion/issues
• Wiki: https://github.com/castledking/Axion/wiki
• Discord: https://discord.com/invite/pCKdCX6nYr
• Website: https://castled.codes/axion/

Axion is licensed under the GPL-3.0 license.