About Worldgen Devtools
From ModrinthA 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 Instead, they are marked as outdated, so that they don't have an effect on world generation and can't be referenced from other datapack files. Existing chunks can still use the outdated entries though, until the world is reopened.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:
Highlights
From source dataGame 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
| Loader | Game versions | Newest |
|---|---|---|
| Fabric | 1.21.1 to 26.4-snapshot-2 (7 versions) | 26.4-snapshot-2 |
From 8 recorded builds of Worldgen Devtools.
Recent builds
| Build | Released | Game versions | Loaders |
|---|---|---|---|
| 1.4.2+26.3 | 2026-10-03 | 26.3 | Fabric |
| 1.4.2+26.1 | 2026-10-03 | 26.1 | Fabric |
| 1.4.2-26.4-snapshot-2 | 2026-10-03 | 26.4-snapshot-2 | Fabric |
| 1.4.1+26.4-snapshot-1 | 2026-09-22 | 26.4-snapshot-1 | Fabric |
| 1.1.2+1.21.1 | 2026-09-20 | 1.21.1 | Fabric |
| 1.4.1+26.1 | 2026-09-20 | 26.1 | Fabric |
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 catalogWorld generation
Changes or adds to how new terrain, biomes and structures are created.
Works on a server
From source side supportModrinth 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












