Custom Dimensions

Custom Dimensions: The Multiverse Engine

Custom Dimensions is a fully server-side Fabric mod that lets server administrators create custom dimensions, define physical portal frames, and connect worlds with persistent two-way gateways.

Players can join with an unmodified vanilla clientonly the server needs the mod and Fabric API.

Supported Minecraft versions

• Minecraft 1.21 through 1.21.11
• Minecraft 26.1 through 26.1.2
• Minecraft 26.2

Use the JAR made for your Minecraft version. All releases use Fabric Loader.

Features

Create custom dimensions

Create void, Overworld-style, Nether-style, or End-style dimensions directly from the server. The mod writes the datapack definition and creates the dimension folder immediately.

A full server restart is required after creation so Minecraft can load the new dimension into the live world registry.

Persistent two-way portals

The first time a player enters an activated portal, the mod:

1. Finds or creates a safe destination portal.
2. Creates a safety platform when necessary.
3. Gives both physical portals unique UUIDs.
4. Stores a reciprocal link between the source and destination.
5. Uses that exact portal pair for return travel.

After arriving, step completely out of the destination portal, wait for the configured cooldown, and enter it again to return. The cooldown prevents the player from instantly bouncing between dimensions while still standing inside the portal.

Portal pairs are saved per world and survive server restarts.

Flexible physical frames

• Build an empty vertical rectangular frame from the configured frame block.
• The default allowed interior is 23 through 2121 blocks.
• The top, bottom, left side, and right side must be complete.
• The four corner blocks are optional.
• Use the configured igniter on any frame block.
• Frames may face either the X or Z direction.

One portal definition can activate multiple physical frames. Every activated frame receives its own UUID and its own reciprocal destination portal.

Coordinate scaling

Each portal definition supports a coordinate multiplier from 0.001 through 1000.0.

• 1.0 keeps the same coordinates.
• 0.125 converts Overworld coordinates to Nether-style 1:8 coordinates.
• 8.0 performs the inverse conversion.

The generated return portal automatically uses the inverse scale.

Server-side particles

Active portal interiors are filled with colored vanilla dust particles. The particle color comes from the RGB value supplied to /portal link.

Particle density, interval, and spread are configurable. Because particles are sent by the server, players do not need a client mod.

Live command suggestions

TAB completion includes:

• Registered block IDs
• Registered item IDs
• Every dimension currently loaded by the server
• Dimensions supplied by vanilla, datapacks, other mods, and Custom Dimensions

Enhance your server setup! Check out my other server-side mods over at : Fabric Server Essentials

Commands

/dimension create

/dimension create <name> <void|overworld|nether|end>

Example:

/dimension create pvp_arena void

This creates customdimensions:pvp_arena. Restart the server before using it as a portal target.

/portal link

/portal link <id> <frame_block> <igniter_item> <target_dimension> <RRGGBB> <light_level> [scale]

Example:

/portal link arena_gate minecraft:obsidian minecraft:flint_and_steel customdimensions:pvp_arena FF0000 15 1.0

Then build the matching frame and use flint and steel on any frame block.

If several definitions use the same frame block and igniter, physical ignition selects the alphabetically first definition. Use /portal activate when you need to select a specific definition.

Server configuration

The mod generates:

config/custom_dimensions.json

Default configuration:

{
  "schemaVersion": 1,
  "commandPermissionLevel": 4,
  "portalIgnitionPermissionLevel": 0,
  "particlesPerSample": 8,
  "particleIntervalTicks": 5,
  "particleSpread": 0.32,
  "frameDetectionRange": 21,
  "frameValidationIntervalTicks": 40,
  "portalCooldownTicks": 80,
  "destinationSearchRadius": 16
}

Configuration options

Permission level 0 allows everyone. Permission level 4 requires a server owner or operator level 4.

Restart the server after editing this file. Invalid configuration files are backed up and replaced with safe defaults.

Data files

Use the commands to manage portal definitions. Manual edits to portal_links.json or the per-world portal-instance file are not recommended while the server is running.

Examples

PvP arena

/dimension create pvp_arena void

Restart the server, then run:

/portal link arena_gate minecraft:obsidian minecraft:flint_and_steel customdimensions:pvp_arena FF0000 15 1.0

Resource world with Nether-style scaling

/dimension create resource_world overworld

Restart the server, then run:

/portal link resource_gate minecraft:iron_block minecraft:stick customdimensions:resource_world 00FF00 10 0.125

Purple gateway to the Nether

/portal link nether_gate minecraft:crying_obsidian minecraft:amethyst_shard minecraft:the_nether A020F0 15 0.125

Installation

1. Install the correct Fabric Loader version for your server.
2. Install the matching Fabric API.
3. Put the correct Custom Dimensions JAR in the server's mods/ folder.
4. Start the server once to generate the configuration files.
5. Create a dimension, restart the server, define a portal, and build its frame.

Only install one Custom Dimensions JAR. Use the build matching your exact Minecraft version.

Notes

• The mod is server-side; vanilla clients can connect.
• A newly created dimension requires one full server restart before portal use.
• The portal interior must be empty when activated.
• Breaking a required frame block deactivates that physical portal.
• To use the return side, leave the portal interior and re-enter after the cooldown.