Set up StackMob on your Minecraft server

StackMob merges nearby mobs of the same kind into one entity that carries a count, so a pen of thirty cows becomes one cow tagged with its stack size. Fewer entities means less work for the server. It is a plugin for Paper or Purpur and installs from the Plugins tab.

Checked against StackMob 5.10.8, the latest release on its Modrinth page, which lists Paper 1.21.11 to 26.2, October 2026.

What you need

• A Paper or Purpur server. Vanilla servers have no Plugins tab; switch software in JAR Manager first (see Change your Minecraft version or mod loader).
• Minecraft 26.1 or newer. StackMob 5.10.5 to 5.10.8, the builds we checked, are compiled for Java 25, and the project's build file sets Java 25. Our panel picks the Java version from your Minecraft version and uses Java 25 only for the 26.x releases.

Install it

1. Open the Plugins tab and leave the Modrinth button selected.
2. Search for StackMob and click Install on the result by ploppyperson. Skip StackMob Fabric, which is a Fabric mod.
3. Use Restart on the Console tab, then open the Installed view to confirm it is listed.

First run

The plugin writes plugins/StackMob/config.yml. These defaults decide what you will see:

• stack.max-size is 30, so a stack never holds more than thirty mobs.
• stack.interval is 100 ticks, so the plugin looks for mobs to merge every five seconds.
• stack.merge-range is [10,10,10], the area searched around each mob.
• stack.threshold starts stacking only once 5 mobs are nearby.
• types-blacklist skips villagers, water mobs and raiders.
• reason-blacklist lists spawn reasons that never stack. It ships with SHOULDER_ENTITY and NATURAL.
• display-name.visibility is NEARBY, so the stack tag shows within 12 blocks.
• wait-to-stack holds back stacking for zombies, skeletons, zombified piglins, creepers and endermen that came from a spawner, so grinders are not broken.

Killing a stack removes a random 1 to 5 mobs per kill (the STEP death method, min-step 1 and max-step 5), and drops and experience are multiplied for the stack. Swap the priority values under death if you want SINGLE, where one mob dies, to come first.

Edit the file in File Manager with the server stopped, or save it and run sm reload in the Console.

Commands

/stackmob has the alias /sm and is limited to the stackmob.admin permission, so run these from the Console. Useful subcommands:

• sm about and sm stats show plugin information and statistics.
• sm reload reloads the config files.
• sm forcestack marks all currently loaded mobs that are not blacklisted as stackable.
• sm tool gives you the stacking tool, and sm spawn spawns a stack. Both are for players in the game.

Common problems

• Mobs are not stacking. Check that at least 5 are within the merge range, that they can see each other (line-of-sight is true), and that their type and spawn reason are not in a blacklist. Because NATURAL is blacklisted by default, naturally spawned mobs stay separate until you remove it.
• A mob farm stopped working. Raise wait-to-stack.wait-time, which is the number of stack checks a new mob skips (5 by default).
• The plugin did not load. Read the Console. A Java version error there means the build needs a newer Java than the server runs, so check your Minecraft version against the list above.