
Biome Modifier for Fabric
A library mod that allows users utilize datapacks to modify biomes easily and compatibly.
Screenshots




About this Mod
Biome-Modifier-for-Fabric

Abstract
This is a library mod that allows users utilize datapacks to modify biomes easily and compatibly.
Usage for Developers
We all know that for Forge modpacks, developers can utilize the following example to modify biomes:
{
"type": "forge:add_features",
"biomes": "#forge:is_plains",
"features": [
"emeraldcraft:wild_cabbage",
"emeraldcraft:wild_chili"
],
"step": "vegetal_decoration"
}
Let's make this work for Fabric!
Datapack developers should put all biome modifiers (with format *.json) on data/<modid>/biome_modifiers/ directory. With this mod, all biome modifiers will be applied on each biome.
All biome modifiers should follow this format:
{
"type": "<modifier type>",
"biomes": "<registry name of a single biome/list of registry names of biomes/a tag of biomes>",
"priority": priority,
"<other keys...>": "<other values...>"
}
Where type stands for the type of biome modifiers, and biome stands for all biomes to be modified.
Notice that priority field is optional. The smaller it is, the earlier it will be applied to the biomes (for example, modifiers with priority 99 will be applied earlier than modifiers with priority 100). The default value is 1000.
Different Types of Biome Modifiers
We provide 9 different types of biome modifiers currently:
biome_modifier:none
This type allows developers to replace other biome modifiers in other datapacks.
{
"type": "biome_modifier:none"
}
biome_modifier:add_features
This biome modifier adds all placed features mentioned in features field to target biomes.
If any placed feature is missing from the registry, an error will be logged (won't crash the game with safe mode).
{
"type": "biome_modifier:add_features",
"biomes": "<registry name(s) of biomes>",
"features": "<registry name of a single feature/list of registry names of features>",
"step": "<step of decoration generation>"
}
biome_modifier:remove_features
This biome modifier removes all placed features mentioned in features field from target biomes.
If any placed feature is missing from the target biomes, a warning will be logged and won't crash the game.
If any placed feature is missing from the registry, an error will be logged (won't crash the game with safe mode).
{
"type": "biome_modifier:remove_features",
"biomes": "<registry name(s) of biomes>",
"features": "<registry name of a single feature/list of registry names of features>",
"step": "<step of decoration generation>"
}
biome_modifier:add_spawns
This biome modifier adds all entity spawns mentioned in spawns field to target biomes.
If any entity type is missing from the registry, an error will be logged (won't crash the game with safe mode).
{
"type": "biome_modifier:add_spawns",
"biomes": "<registry name(s) of biomes>",
"spawners": [
{
"type": "<registry name of a single entity type>",
"weight": weight,
"minCount": minCount,
"maxCount": maxCount
}
//If you only add one spawner, you can also replace the list with the only object.
]
}
biome_modifier:remove_spawns
This biome modifier removes all entity spawns mentioned in entity_types field from target biomes.
If any entity type is missing from the target biomes, a warning will be logged and won't crash the game.
If any entity type is missing from the registry, an error will be logged (won't crash the game with safe mode).
{
"type": "biome_modifier:remove_spawns",
"biomes": "<registry name(s) of biomes>",
"entity_types": [
"<registry name of a single entity type>"
//If you only remove one spawner, you can also replace the list with the only string.
]
}
biome_modifier:add_spawn_costs
This biome modifier adds all entity spawns mentioned in spawn_costs field to target biomes.
Unlikely to biome_modifier:add_spawns, this modifier adds spawns to spawn costs (aka. spawn potential, spawn density).
If any entity type is missing from the registry, an error will be logged (won't crash the game with safe mode).
{
"type": "biome_modifier:add_spawn_costs",
"biomes": "<registry name(s) of biomes>",
"spawn_costs": {
"<registry name of a single entity type>": {
"charge": charge,
"energy_budget": energy_budget
}
}
}
biome_modifier:remove_spawn_costs
This biome modifier removes all entity spawns mentioned in entity_types field from target biomes.
Unlikely to biome_modifier:remove_spawns, this modifier removes spawns to spawn costs (aka. spawn potential, spawn density).
If any entity type is missing from the target biomes, a warning will be logged and won't crash the game.
If any entity type is missing from the registry, an error will be logged (won't crash the game with safe mode).
{
"type": "biome_modifier:remove_spawn_costs",
"biomes": "<registry name(s) of biomes>",
"entity_types": [
"<registry name of a single entity type>"
//If you only remove one spawner, you can also replace the list with the only string.
]
}
biome_modifier:add_carvers
This biome modifier adds all carvers mentioned in carvers field to target biomes.
If any carver is missing from the registry, an error will be logged (won't crash the game with safe mode).
{
"type": "biome_modifier:add_carvers",
"biomes": "<registry name(s) of biomes>",
"carvers": "<registry name of a single carver/list of registry names of carvers>",
"step": "<step of carver generation>"
}
biome_modifier:remove_carvers
This biome modifier removes all carvers mentioned in carvers field from target biomes.
If any carver is missing from the target biomes, a warning will be logged and won't crash the game.
If any carver is missing from the registry, an error will be logged (won't crash the game with safe mode).
{
"type": "biome_modifier:remove_carvers",
"biomes": "<registry name(s) of biomes>",
"carvers": "<registry name of a single carver/list of registry names of carvers>",
"step": "<step of carver generation>"
}
Examples
We provide 3 example datapacks for our mods:
Extra Ores
This datapack adds extra ore blocks to the overworld.

No Ore in Overworld
This datapack removes all ore blocks to the overworld, and only keeps ore veins for players to obtain ores.

Zombies in the Nether
This datapack makes zombie able to spawn in the nether.

Available Versions
How to Install Biome Modifier for Fabric on Your Server
Order Server
Order a Minecraft Java server with at least 4 GB RAM (6 GB recommended).
Set fabric Loader
In the panel under "Egg", select the fabric loader and matching Minecraft version (1.21.3).
Install Mod
Open the mod browser in the dashboard and search for "Biome Modifier for Fabric". Click "Install" – done! Alternatively, upload the .jar via SFTP to the /mods folder.
Compatibility
Mod Loaders
Minecraft Versions
1.21.3, 1.21.2, 1.21.1 (+8 more)
Server-side
✓ RequiredRecommended RAM
6 GB(min. 4 GB)Frequently Asked Questions
Biome Modifier for Fabric server crashes on startup – what to do?
Most common cause: wrong fabric version or insufficient RAM. Check the server log (latest.log) for "OutOfMemoryError" or "Mixin" errors. With Mado Hosting: ensure at least 4 GB RAM is allocated and the loader matches the mod version (1.21.3). You can switch loaders with one click in the panel.
Is Biome Modifier for Fabric compatible with fabric?
Biome Modifier for Fabric officially supports fabric for Minecraft 1.21.3, 1.21.2, 1.21.1. The Mado dashboard automatically detects incompatible loader combinations.
Server lagging with Biome Modifier for Fabric – how to optimize performance?
Recommended RAM: 6 GB (per 5 players). Use /spark profiler to check if Biome Modifier for Fabric consumes the most tick time. Common fixes: reduce server view-distance to 8-10, install "performant" or "starlight" as supplementary mods on Forge. With Mado Hosting, your server runs on NVMe SSDs with dedicated CPU cores for minimal latency.
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Rent Modded Server
Install Biome Modifier for Fabric with just one click on your server.