Mob proof crystals
Mob proof crystals is a Fabric utility that spawnproofs large areas of terrain using a single end crystal placed on obsidian.
What it does
A single end crystal placed on obsidian marks a cubic area of 64 by 64 by 64 blocks, and the mod makes that area spawnproof. The area starts 64 blocks above the crystal and extends 32 blocks in each horizontal direction, so a crystal can cover terrain that lies well below the surface. Players who want to hide spawnproof space underground can use this to keep mobs from spawning there.
The lower-limit option sets how far the affected area extends below the crystal, with a default of one layer below the end crystal's obsidian. A value of 16 lowers the area by 16 blocks. Settings live in a crystal.properties file created in the .minecraft folder, where the affected area can also be expanded by moving its Y coordinate. Crystals can be renamed to avoid unwanted behavior in the world.
Mob proof crystals is licensed under the GNU General Public License v3.0 only and is open source, with its source code and issue tracker publicly linked. It is published for Fabric only, across 19 release versions spanning 1.17 – 26.3. The mod is server-side only, so players join without installing it.
Key features
Spawnproof cubic areas
One end crystal on obsidian makes a 64 by 64 by 64 block cube spawnproof, placed 64 blocks above the crystal.
Lower-limit setting
The lower-limit option controls how far below the crystal the affected area extends, so the spawnproof zone can reach underground.
Renamable crystals
Crystals can be renamed, which helps keep them from changing behavior in a world that already uses that name.
Configurable Y coordinate
The Y coordinate of the affected area can be moved in crystal.properties, expanding or shifting the spawnproof zone.
Compatibility
Latest build for each game version and loader.
26.x5 of 5 versions with builds
1.21.x2 of 2 versions with builds
1.20.x3 of 3 versions with builds
1.19.x5 of 5 versions with builds
1.18.x3 of 3 versions with builds
1.17.x1 of 1 version with builds
Only full game releases are shown. This mod publishes no snapshot builds.
Use cases
Who it’s for: The mod suits server owners and builders who want to control mob spawning across large terrain areas using end crystals on obsidian, and who are comfortable editing a properties file.
How it compares
FastCrystalSpin is client-side only and open source under the MIT License, built for 1.20.1 – 26.3, so it changes nothing on the server. Smaller Crystals is client-side only, published for 1.21 – 1.21.5, and is not open source. Crystal_haerts is a client and server mod for 1.21.8 – 1.21.11, and is not open source.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Mob proof crystals | Fabric | 1.17 – 26.3 | Server-side only | 2026-09-25 |
| FastCrystalSpin | Fabric | 1.20.1 – 26.3 | Client-side only | 2026-09-29 |
| Smaller Crystals | Fabric | 1.21 – 1.21.5 | Client-side only | 2025-12-31 |
| Crystal_haerts | Fabric | 1.21.8 – 1.21.11 | Client and server | 2026-02-14 |
Questions
Does Mob proof crystals need to be installed on the client?
Which Fabric version does the latest file target?
How is the spawnproof area positioned relative to the crystal?
In the catalog
Mob proof crystals is one of 36,990 Utility mods on ModsFinder, and one of 25,772 Utility mods for Fabric. 8,071 mods support Minecraft 26.3.
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What the author says
This mod allows to spawnproof areas of 64x64x64 blocks with just one end crystal (cubic, not spherical). Each crystal you place in the world creates an area that starts from the block it is placed to 64 blocks above vertically and 32 blocks in each horizontal direction (north, east, south, west). This is mainly…
Official listing
- Modrinth page
- modrinth.com/mod/mobproofcrystals
- Owner
- john-development
- Published
- 2021-06-26
- Updated on Modrinth
- 2026-09-25
- Facts verified
- 2026-10-15