MobStacker
by frikinjay
MobStacker is a server-side optimization mod that merges nearby similar mobs into single stacked entities to lower the number of entities a world must process.
What it does
Mobs of the same kind that stand close together are combined into one stack, so a crowded spawn area keeps fewer physical entities loaded. The mod is aimed at servers with high mob density, large player bases and many entity-adding mods, where entity handling is a common cause of lag. A mob cap module limits how many mobs can accumulate, and the config file lets server owners tune the stacking behaviour further.
MobStacker needs Almanac and Let Me Despawn to run. The commands are gated behind operator permission level 2 and use the mobstacker prefix. A stacked entity carries a StackData tag, and setting CanStack to 0 on a mob keeps it out of stacking. Gains depend on server hardware, player count and the other mods installed, so the size of the improvement varies from server to server.
The project is open source under the GNU Lesser General Public License v3.0 only, and its source code and issue tracker are public. Files are published for Fabric, Forge, NeoForge and Quilt across 10 release versions 1.20.1 – 1.21.5, with snapshot builds also published.
Key features
Mob stacking
Similar mobs close to each other are merged into one stacked entity, which reduces the physical entity count.
Mob cap management
A mob cap module controls how many mobs can build up in an area, and the config file adjusts the limits.
Stack exclusion tag
Setting CanStack to 0 on an entity prevents it from being stacked with others.
Operator commands
Commands use the mobstacker prefix and require operator permission level 2.
Gallery
Compatibility
Latest build for each game version and loader.
1.21.x6 of 6 versions with builds
1.20.x4 of 4 versions with builds
This mod also publishes snapshot builds. Snapshots are not shown in the matrix.
Requirements
Dependencies declared by the latest file for each loader.
Required 2
Use cases
Who it’s for: Server owners running large or heavily modded worlds, and operators who want to tune mob stacking and mob caps through the config file.
How it compares
Entity Cleaner is a server-side helper that also reduces entity load, under All rights reserved and for 1.17 – 26.2 on Fabric, Forge, NeoForge and Quilt. Farm Friendly Mob Stacking covers 1.21.6 – 26.2 and is also server-side, with an All rights reserved license. NovaStack Performance+ is a client-side Fabric mod under the MIT License for 1.21.10, so it does not touch the server. MobStacker stays on the server and is open source.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| MobStacker | Fabric, Forge, NeoForge and Quilt | 1.20.1 – 1.21.5 | Server-side only | 2025-04-09 |
| Entity Cleaner | Fabric, Forge, NeoForge and Quilt | 1.17 – 26.2 | Server required, client optional | 2026-07-04 |
| Farm Friendly Mob Stacking | Fabric, Forge, NeoForge and Quilt | 1.21.6 – 26.2 | Server required, client optional | 2026-08-12 |
| NovaStack Performance+ | Fabric | 1.21.10 | Client-side only | 2026-06-04 |
Questions
Does MobStacker need to be installed on the client?
Which dependencies does MobStacker require?
Can stacking be turned off for a specific mob?
Which game versions are supported?
In the catalog
MobStacker is one of 3,545 Optimization mods on ModsFinder, and one of 2,575 Optimization mods for Fabric. 15,307 mods support Minecraft 1.21.5.
More from frikinjay
Similar mods
What the author says
MobStacker is a performance Minecraft mod to optimize entity handling, addressing a common cause of performance issues in vanilla and modded environments. By intelligently "stacking" similar mobs in close proximity, MobStacker significantly reduces server load and enhances client-side performance without compromising…
Official listing
- Modrinth page
- modrinth.com/mod/mobstacker
- Owner
- frikinjay
- Published
- 2024-10-11
- Updated on Modrinth
- 2025-04-09
- Facts verified
- 2026-10-15