Source-checkedWorld generation

Worldgen Devtools

by jacobsjo · for Minecraft

A mod that aids in the development of world generation data packs and mods. Allows reloading worldgen data packs in-game and resetting chunks. Colors jigsaw blocks by name and target.

9.8KDownloads
32d agoLast updated
MITLicense
FabricLoaders

About Worldgen Devtools

From Modrinth

A mod that aids in the development of world generation data packs and mods. Allows reloading worldgen data packs in-game and resetting chunks. Colors jigsaw blocks by name and target.

Worldgen Devtools

This is a mod that provides tools simlifying the creation of worldgen datapacks and mods.

Registry (worldgen) Reloading

Needs be enabled per world using the reloadRegistries gamerule.

Warning: While this should be fairly stable, this tool can probably still corrupt your worlds. So only enable in testing worlds

Allows the reloading of registry content (such as all worldgen data) using the /reload command, or when enabling or disabling a datapack using the /datapack command. Without this mod, the world needs to be reopened for changes to take effect.

Entries are never removed from registries, even when no longer present in the loaded datapacks. Instead, they are marked as outdated, so that they don't have an effect on world generation and can't be referenced from other datapack files. Existing chunks can still use the outdated entries though, until the world is reopened. The world-height and noise shape (i.e. height and cell size) can't be reloaded.

Client Syncronization

Some reloaded data affects the client, such sa biome colors, dimension types, and armor trims. In multiplayer, dimension and biome effects need to be synconized. This causes the client to redraw all chunks. If this behaviour is undesireble, it can be disabled using the syncAfterRegistryReload gamerule.

Reset Chunks

The /resetchunks [<range>] command resets the chunks surrounding the player in the specified range - regenerating it with the current worldgen data and settings. Defaults to 0 (i.e. only the current chunk). If you want to reset a structure, you need to reset the chunk of the structure start.

Note: This implementation actually used the normal worldgen thread, and thus has much better performance than the unregistered vanilla command.

Colored Jigsaw Blocks

Colors Jigsaw blocks based on their specified "Name" or "Target Name". If a "Name" other than minecraft:empty is set, the jigsaw block is colored based on the hash of the "Name". Otherwise, if a "Target Name" other than minecraft:empty is set, the jigsaw block is colored based on the hash of the "Target Name".

If both "Name" and "Target Name" are set to minecraft:empty the jigsaw block is rendered deactivated, with grayed out arrows and connectors.

In the inventory, if a jigsaw block has stored NBT (Shift+Pick), then it is rendered with the associated color and a tooltip indicated the "Name", "Target Pool", and "Target Name".

Get Density Command

Command to debug the values of density functions are any position.

/getDensity density_function <df> [<pos>]

Returns the value of the density function df at the specified postion (or the position of the player)

/getDensity noise_router <entry> [<pos>]

Returns the value of the density function specified in the given entry of the noise router of the current dimension at the specified postion (or the position of the player)

Profiling of Worldgen Performance

The time it took to generate each step of each chunk is recorded and saved in each chunk. To access it, use the /chunkprofiling <range> command. Range controlls the amount of chunks to average the performance over; defaults to 0.

Locate Feature

Use /locate feature <configured_feature> to locate a configured feature nearby. If the current chunk contains the feature multiple times, it will list the up to 5 closest positions. This only works if the chunk is generated while this mod is installed.

Logging improvements

  • Empty height ranges in placed features also log the placed feature that causes the problem.

Chase

The /chase command provides options to syncronize of the player positions between two different instances of Minecraft. Usefull for comparing differences in worldgen. This is a vanilla command, simply registered by this mod.

Gamerules

Gamerules added by this mod:

Read the full description on Modrinth →

Highlights

From source data

Game versions

Supports 79 Minecraft versions, the newest being 26.4-snapshot-2.

Loaders

Runs on Fabric.

Footprint

Rated a light load on a server.

Worldgen Devtools on Nxeon

From our catalogue
One-click install
Supported on Nxeon Minecraft servers. We download it from Modrinth, place it, and restart the server.
Server side
Optional on the server
Server type needed
Fabric
Server load
light
Smallest plan we suggest
Minecraft — 2 GB (2 GB RAM). This follows our own load rating above, not a benchmark.
Latest build
1.4.2+26.3, released 2026-10-03

Game versions by loader

LoaderGame versionsNewest
Fabric1.21.1 to 26.4-snapshot-2 (7 versions)26.4-snapshot-2

From 8 recorded builds of Worldgen Devtools.

Recent builds

BuildReleasedGame versionsLoaders
1.4.2+26.32026-10-0326.3Fabric
1.4.2+26.12026-10-0326.1Fabric
1.4.2-26.4-snapshot-22026-10-0326.4-snapshot-2Fabric
1.4.1+26.4-snapshot-12026-09-2226.4-snapshot-1Fabric
1.1.2+1.21.12026-09-201.21.1Fabric
1.4.1+26.12026-09-2026.1Fabric

Dependencies

  • Required: modrinth project P7dR8mSH (modrinth, not in our catalogue)

Declared by the newest build that lists any. Required ones are installed with it on one-click installs.

Run Worldgen Devtools on a Minecraft server

Pick a server or deploy a new one above; it is installed in one click.

What kind of mod it is

From the catalog
Listed on Modrinth as “Mods”

World generation

Changes or adds to how new terrain, biomes and structures are created.

Works on a server

From source side support

Modrinth lists server-side support for Worldgen Devtools as optional: it can run on a server, but isn’t required there.

Compatibility

Game
Minecraft
Loaders
Fabric
Runs on
Serveroptional on the server
Game versions
26.4-snapshot-2 and 78 earlier

Verified at the source

  • ✓ModrinthOfficial listing, checked 2026-10-04Open ↗
  • ✓Authorjacobsjo, as published on Modrinth
  • ✓LicenseMITFree

Worldgen Devtools, answered

Generated from the mod’s own source data.

Do my players need to install Worldgen Devtools?

Modrinth lists server-side support for Worldgen Devtools as optional: it can run on a server, but isn’t required there.

Which loaders does it support?

Fabric.

Is it free?

Yes. Worldgen Devtools is free to download from Modrinth. Its license is MIT.

How do I add it to my Nxeon server?

Use “Add to a server” on this page, or open NxLabs from your dashboard. We install it, restart your server and switch it on.

NxLabs

Run Worldgen Devtools on a Minecraft server.

Deploy in about a minute from $4.99 a month, then add Worldgen Devtools in one click.