How to Host a Cobblemon Server (Fabric)

What Is Cobblemon?

Cobblemon is a Pokemon mod for Minecraft built from the ground up on Fabric (with a Forge port also available). Unlike Pixelmon, which is a Forge-only mod with its own legacy codebase, Cobblemon is a modern alternative that takes advantage of Fabric's lightweight architecture. Pokemon spawn in biome-appropriate locations, players catch them, battle trainers, and evolve their team. The mod supports Minecraft 1.20.1 through 1.21.x depending on the release, and it is actively developed with frequent updates.

Fabric's lower overhead makes Cobblemon servers lighter than equivalent Pixelmon servers. If you want to host a Cobblemon server on Fabric, the process is clean and the performance profile is favorable, especially when you add Fabric's ecosystem of optimization mods.

Server Requirements

Fabric and Java Version

Cobblemon runs on Fabric Loader. For Minecraft 1.20.x, use Java 17. For Minecraft 1.21+, use Java 21. Install Fabric Server by downloading the Fabric installer from fabricmc.net, running it in server mode, and placing the Cobblemon jar plus Fabric API into the mods/ folder. Cobblemon requires Fabric API as a dependency, so do not skip it.

RAM Allocation

Player Count	Minimum RAM	Recommended RAM
1–5 players	3 GB	4 GB
6–15 players	4 GB	6 GB
15–30 players	6 GB	8 GB

Cobblemon on Fabric is remarkably lightweight. The mod itself adds Pokemon entities, spawn logic, and battle calculations, but Fabric's minimal loader overhead keeps the total footprint low. RAM scales primarily with player count and how many Pokemon are spawned at any given time. The RAM calculator helps fine-tune your allocation when you host a Cobblemon server on Fabric with additional mods.

Downloading and Installing

1. Download and run the Fabric server installer for your Minecraft version.
2. Download Cobblemon and Fabric API from Modrinth or CurseForge.
3. Place both jars in the mods/ folder.
4. Accept the EULA in eula.txt.
5. Start the server.

java -Xms3G -Xmx4G -jar fabric-server-launch.jar nogui

First boot generates Cobblemon config files under config/cobblemon/. The startup is fast, usually under a minute, thanks to Fabric's quick loading pipeline.

Config Tweaks

Spawn Rates and Biome Mapping

Cobblemon maps Pokemon spawns to biomes. The spawn config files control which Pokemon appear where, their rarity, and level ranges. If players report empty biomes, check that the spawn files include entries for those biome IDs. Custom world generators that rename biomes can break spawn mappings.

Battle Mechanics

Cobblemon battles happen in real-time on the server. The battle engine processes moves, damage calculations, and status effects per tick. With many simultaneous battles, CPU usage increases. There is no built-in battle limit, but you can set one through a server plugin or datapack if needed.

Optimization Mods

Fabric's ecosystem includes Lithium (tick optimization), Starlight (light engine rewrite), and FerriteCore (memory reduction). Adding all three alongside Cobblemon improves performance noticeably. These mods are server-side compatible and require no client installation.

Common Issues

Fabric API Version Mismatch

Cobblemon requires a specific minimum Fabric API version. If you see errors about missing API modules on startup, update Fabric API to the latest build for your Minecraft version. This is the single most common installation mistake.

Pokemon Not Spawning

If Pokemon stop spawning, check the entity cap in server.properties. Vanilla mobs plus Cobblemon entities can hit the cap, leaving no room for new Pokemon. Lower vanilla mob caps to give Cobblemon room to spawn, or increase the total cap if your RAM allows it.

Performance Tuning

Set view-distance=10 and simulation-distance=6. Players need to see Pokemon at a distance, so a reasonable view distance helps. Simulation distance can stay tighter since Pokemon AI only needs to run when players are nearby.

JVM flags for Fabric:

java -Xms3G -Xmx4G -XX:+UseG1GC -XX:MaxGCPauseMillis=130
-XX:+UnlockExperimentalVMOptions -XX:G1NewSizePercent=40
-XX:G1MaxNewSizePercent=50 -XX:G1HeapRegionSize=16M
-XX:G1ReservePercent=15 -XX:InitiatingHeapOccupancyPercent=20
-XX:+AlwaysPreTouch -jar fabric-server-launch.jar nogui

See our JVM flags guide for the full explanation. For a comparison with the Forge-based alternative, read our Pixelmon guide. If you want to combine Cobblemon with other mods, the Better MC guide explains vanilla-plus hosting on a similar Fabric base.

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