CobbleStacker
CobbleStacker merges nearby identical mobs and dropped items on the server, so a crowded spawner area keeps fewer entities loaded.
What it does
Stacking runs automatically: when identical mobs or ground items sit close together, they combine into one entity that shows a nametag with the real count, such as x16 Zombie. Merged mobs keep their attributes, variant, color, size, baby or adult state, tamed owner and profession. Ground items can exceed the vanilla per-stack limit, up to 1024 per stack.
Death behavior is configurable. KILL ONE removes a single mob from the stack and respawns the rest with a reduced count, while KILL removes the whole stack, with drops and experience multiplied by the number of mobs. Mobs with name tags are never stacked, and a blacklist filters entity types and worlds. A built-in auto-clear removes old item stacks after a set time, and a whitelist protects valuable items.
The mod works with Cobblemon: Pokemon are automatically excluded from stacking. It targets spawner output and general server lag. It is released under the MIT License and is not open source. Builds exist for Fabric and NeoForge, for 1.21 and 1.21.1, and 1.1.0 is the latest file for both loaders.
Key features
Automatic mob merging
Nearby identical mobs combine into one entity with a visible count in its nametag.
Attribute preservation
Merged mobs keep their variant, size, age, tamed owner and profession.
Configurable death handling
KILL ONE and KILL modes control whether a death removes one mob or the whole stack.
Item stacking past vanilla limits
Ground items of the same type merge up to 1024 per stack, and old stacks are cleared after a set time.
Blacklist and whitelist
Entity types and worlds can be excluded, and valuable items can be protected from auto-clear.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Use cases
Spawner farms
Spawner output piles up on the ground; stacking keeps the loaded entity count lower.
Item-heavy bases
Drop-heavy farms leave many item stacks behind, which merge and clear on a timer.
Who it’s for: Server owners running large spawner or farm setups who want lower entity load, and Cobblemon servers that need Pokemon kept out of stacking.
How it compares
No Item Merge is a Fabric server-side mod for 1.21.1, released under the MIT License and not open source. ItemStacker is also a Fabric server-side mod under the MIT License and not open source, but it targets 1.21.11. LagSweeper Datapack runs on Fabric, Forge, NeoForge and Quilt for 1.21.5, under All rights reserved, and needs the server while clients may skip it.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| CobbleStacker | Fabric and NeoForge | 1.21 – 1.21.1 | Server-side only | 2026-03-26 |
| No Item Merge | Fabric | 1.21.1 | Server-side only | 2026-05-03 |
| ItemStacker | Fabric | 1.21.11 | Server-side only | 2026-06-06 |
| LagSweeper Datapack | Fabric, Forge, NeoForge and Quilt | 1.21.5 | Server required, client optional | 2026-01-29 |
Questions
Does CobbleStacker need to be installed on the client?
Which loaders are supported?
Are Pokemon affected by stacking?
In the catalog
CobbleStacker is one of 3,545 Optimization mods on ModsFinder, and one of 2,575 Optimization mods for Fabric. 32,366 mods support Minecraft 1.21.1.
More from MarcoErCarrozza
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What the author says
CobbleStacker is a server-side Fabric mod for Minecraft 1.21 designed to significantly reduce entity lag by intelligently stacking mobs, ground items, and spawners. Fully compatible with Cobblemon — all Pokemon are automatically excluded from stacking.
Official listing
- Modrinth page
- modrinth.com/mod/cobblestacker
- Owner
- MarcoErCarrozza
- Published
- 2026-02-06
- Updated on Modrinth
- 2026-03-26
- Facts verified
- 2026-10-15