Axion

What is it?

Axion is an open-source Fabric building tool for Minecraft, inspired by Axiom. It adds fast in-game editing tools, live previews, symmetry, Magic Select, saved hotbars, and long-range builder utilities.

For multiplayer-safe editing on Paper, pair it with the Axion Paper plugin:

Axion Plugin README

For Minecraft 1.21.11, Axion also has a Fabric dedicated server path using the same main Fabric jar that players install on the client.

Overview

The Fabric mod is the client-side half of Axion. It handles:

• hotbar tool selection
• live region previews
• symmetry anchors and gizmos
• Magic Select templates and masks
• saved hotbars / hotbar workspace flow
• builder modes like replace mode, infinite reach, and no clip
• local singleplayer behavior

For multiplayer editing:

• on Paper, use the Axion Paper plugin
• on Fabric dedicated server, use the same Axion Fabric jar in the server mods folder, but this server path currently only targets Minecraft 1.21.11

Version Support

Fabric client support:

• 1.21.8
• 1.21.9
• 1.21.10
• 1.21.11

Paper plugin support:

• 1.21.8
• 1.21.9
• 1.21.10
• 1.21.11

Fabric dedicated server support:

• 1.21.11 only

Features

• Hotbar-based tools for:
  • Move
  • Clone
  • Stack
  • Smear
  • Erase
  • Extrude
  • Symmetry
• Magic Select with:
  • editable templates
  • shared custom masks
  • searchable block picker
  • brush size control
• Saved hotbars / hotbar workspace:
  • hold Alt to open the saved hotbar overlay
  • scroll or click to switch saved hotbars
  • release Alt to load the selected saved hotbar into your live hotbar
  • the previously active hotbar is saved back automatically
• Fly speed adjustment via Alt menu
  • slider from 100% to 999%
• Builder utilities:
  • replace mode
  • infinite reach
  • no clip
  • far pick block
  • bulldozer
  • fast place
• Preview and selection feedback:
  • pulsing cuboid feedback
  • ghost block previews
  • guide arrows
  • clearer helper text
• Mod Menu integration and in-game config screen

Requirements

For Fabric client:

• Fabric Loader
• Fabric API
• Fabric Language Kotlin

Minecraft version support:

• 1.21.8 through 1.21.11 on the client

For Fabric dedicated server:

• Minecraft 1.21.11
• Fabric Loader
• Fabric API
• Fabric Language Kotlin
• the same Axion Fabric jar that the client uses for 1.21.11

Installation

Fabric Client

1. Install Fabric Loader for your supported Minecraft version (1.21.8 through 1.21.11).
2. Put the Axion mod jar in your client mods folder.
3. Install Fabric API and Fabric Language Kotlin.
4. Launch Minecraft in creative mode.

Fabric Dedicated Server (1.21.11 only)

1. Install Fabric Loader for Minecraft 1.21.11.
2. Put the same Axion Fabric jar in the server mods folder.
3. Install Fabric API and Fabric Language Kotlin on the server.
4. Start the server.

Important:

• the 1.21.11 main Axion Fabric jar is dual-use
• you do not need a separate Fabric server-only Axion jar
• the same file goes in the client mods folder and the Fabric server mods folder

Controls and Usage

Axion is designed around a dedicated hotbar slot workflow.

• Equip the Axion slot to access the tool strip
• Use the selected subtool directly in-world
• Hold Alt while on Axion to open the hotbar tool menu / saved hotbar overlay
• Press Right Shift to open the Axion config screen

Saved hotbars:

• hold Alt to preview saved hotbars
• scroll or click to choose a saved hotbar
• release Alt to load it
• your previous hotbar is saved back automatically

Magic Select:

• Toggle Middle Mouse to Magic Select in the Alt menu
• Use MMB to select blob-like regions before point two
• Use Main Mod + MMB to open Magic Select Templates
• Use Main Mod + Scroll to adjust brush size

Multiplayer

Axion works in three broad modes:

• singleplayer / integrated server
• Paper multiplayer with the Axion Paper plugin
• Fabric dedicated server multiplayer on 1.21.11

Paper is still the more mature multiplayer backend, especially for protection/policy integrations.

Fabric server support on 1.21.11 now covers real authoritative editing, but it is currently only available for that exact Minecraft version.

Notes

• Axion is built for creative-mode building workflows.
• Keep the client and server/plugin on matching compatible versions where possible.
• Fabric dedicated server support currently only exists for 1.21.11.
• Paper plugin support and Fabric client support cover 1.21.8 through 1.21.11.

Links

• Main README: https://github.com/castledking/Axion/blob/main/README.md
• Plugin README: https://github.com/castledking/Axion/blob/main/PLUGIN-README.md
• Modrinth: https://modrinth.com/plugin/axion-paper-plugin
• GitHub: https://github.com/castledking/Axion
• Issues: https://github.com/castledking/Axion/issues
• Wiki: https://github.com/castledking/Axion/wiki
• Website: https://castled.codes
• Discord: https://discord.com/invite/pCKdCX6nYr