CurseForge · Minecraft mod
Mob Spawn Checker
A diagnostic tool that tests and displays real-time mob spawn conditions, diagnostics, and failures to save time during mod development.
Quick answer
Which Mob Spawn Checker release should I use?
Mob Spawn Checker MSC 1.1.3 targets 1.21.1 with NeoForge. The project page does not say whether this file belongs on the client, dedicated server, or both. No extra mods listed for this file.
Where it goes
Is Mob Spawn Checker required on the client, server, or both?
The project page does not say whether this file belongs on the client, dedicated server, or both.
The source does not explicitly classify this release as client-only or server-only.
What else does Mob Spawn Checker MSC 1.1.3 need?
MSC 1.1.3. Change the file and its required mods may change too.
This file does not list any required mods. Do not add a library just because a different file uses it.
This file does not list any required or optional mods.
Before you install it
Add Mob Spawn Checker without breaking your instance.
Built for Mob Spawn Checker MSC 1.1.3. Pick another file and the loader, install side or required mods may change.
- 01
Stick to this file
Use MSC 1.1.3. It targets 1.21.1 with NeoForge; another release may have different loader, side or dependency requirements.
- 02
Bring the mods it needs
This file does not list any required mods. Do not add a library just because a different file uses it.
- 03
Put it on the correct side
The project page does not say whether this file belongs on the client, dedicated server, or both.
- 04
Pick the file you checked
Use the “Get this file” button beside MSC 1.1.3. It opens that exact file at the source.
About this project
What does Mob Spawn Checker add?

Mob Spawn Checker (MSC) is the ultimate diagnostic tool designed for mod developers and modpack creators to save hours of tedious testing. Tired of wandering around your world trying to figure out if your newly added custom mobs are actually spawning? With MSC, you can test and inspect mob spawn mechanics in real-time.

Simply press H to open the mob catalog, select any mob, and run a spawn test. The mod monitors the environment for 5 seconds (for monsters) or 20 seconds (for creatures) and breaks down exactly why a mob is or isn't spawning, highlighting the exact failure step if it gets blocked.
Key Features
- Real-Time Spawn Testing & Diagnostics: Runs active tests to determine if a mob attempts and succeeds in spawning, utilizing an 8-door verification pipeline (Game Rules, Difficulty, Biome/Dimension, Mob Cap, Floor/Terrain, Light Level, Free Space, and World Insertion).
- Comprehensive Catalog & Filters: Search for mobs by their English names regardless of language, filter by favorites, view mobs without spawn eggs, or isolate mod-specific mobs.
- Environment Controls: Quickly toggle between Day, Night, Weather conditions, and teleport to valid biomes or dimensions right from the interface.
- Variant & Custom Support: Switch between mob variants and manually spawn entities in Creative mode. With compatibility for external modded mobs.
- Multi-Language Support: Fully translated into English, Portuguese (BR), German, Spanish (ES), French, Russian, Turkish, and partially Simplified Chinese.

Project description from CurseForge.
Pick your setup
Mob Spawn Checker by Minecraft version and loader
Choose the version and loader you play, then open the matching release.
1.20.1
1 loader buildCheck the dependencies, then try the file in a copied instance before changing a world you care about.
Recent files
Mob Spawn Checker versions and loaders
MSC 1.1.3
mobspawnchecker-1.1.3-v1.21.1.jar
7 Oct 2026
MSC 1.1.3
mobspawnchecker-1.1.3-v1.20.1.jar
7 Oct 2026
MSC 1.1.2
mobspawnchecker-1.1.2-v1.21.1.jar
23 Sept 2026
MSC 1.1.2
mobspawnchecker-1.1.2-v1.20.1.jar
23 Sept 2026
MSC 1.1.1
mobspawnchecker-1.1.1.jar
23 Sept 2026
MSC 1.1.0
mobspawnchecker-1.1.0.jar
13 Sept 2026
MSC 1.1.0
mobspawnchecker-1.1.0.jar
13 Sept 2026
MSC 1.0.0
mobspawnchecker-1.0.0 - v.1.21.1.jar
7 Sept 2026
MSC 1.0.0
mobspawnchecker-1.0.0.jar
7 Sept 2026
Looking for an older file? The official CurseForge project page is in Resources.