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Mod ObserverMinecraft mod for 1.21.11

Mod that checks other mod's presence. Upon joining a server that requires you to install this mod, it checks, if the loaded mods are allowed or not.

client onlynewest supported 1.21.11ManagementSocial
Latest version
3.0.2
Minecraft
1.20.2 to 1.21.11
Java
Java 21+
Loader
Fabric
Licence
MIT
Downloads
11.2k
Updated
9 mo ago
Available on
Modrinth
Space NodeOur hosting

Host Mod Observer servers

One click and Mod Observer is installed with the right loader, on hardware built for it.

  • 1.21.11
  • Fabric
  • One click mod install
  • Loader matched for you
  • Ryzen CPUs
  • NVMe SSD
Deploy a serverFrom €0.90 per GB

Screenshots

Click a screenshot to open it. Screenshots are served from the author’s own host and belong to them.

Minecraft versions

Every version Mod Observer declares support for, newest first, with the Java runtime that version needs.

Other mods
MinecraftThroughJavaEvidenceReleased
1.21.11Fabric21+declared9 Dec 2025
1.21.10Fabric21+declared7 Oct 2025
1.21.9Fabric21+declared30 Sept 2025
1.21.8Fabric21+declared17 Jul 2025
1.21.7Fabric21+declared30 Jun 2025
1.21.6Fabric21+declared17 Jun 2025
1.21.5Fabric21+declared25 Mar 2025
1.21.4Fabric21+declared3 Dec 2024
1.21.3Fabric21+declared23 Oct 2024
1.21.2Fabric21+declared22 Oct 2024
1.21.1Fabric21+declared8 Aug 2024
1.21Fabric21+declared13 Jun 2024
1.20.6Fabric21+declared29 Apr 2024
1.20.5Fabric21+declared23 Apr 2024
1.20.4Fabric17+declared7 Dec 2023
1.20.3Fabric17+declared4 Dec 2023
1.20.2Fabric17+declared20 Sept 2023

Download

From Mod Observer’s own host. Nothing is re-hosted here.

3.0.2release22 Dec 2025

ModObserver-client-3.0.2+mc1.21.11.jar · 0.2 MB · for 1.21.11

Download latest
b566a9ff6515…
Older versions11
  • 3.0.127 Nov 20251.21.10, 1.21.90.2 MB199 downloadseedc2155b03b…Get
  • 2.1.37 Oct 20251.21.11, 1.21.10, 1.21.90.2 MB4.5k downloadsc55827ff866b…Get
  • 2.1.22 Oct 20251.21.9, 1.21.8, 1.21.70.2 MB79 downloads82efd66b462e…Get
  • 2.1.122 Aug 20251.21.6, 1.21.5, 1.21.4, 1.21.3, 1.21.2 +2 more0.2 MB274 downloads1b7b571b4339…Get
  • 3.0.018 Aug 20251.21.8, 1.21.70.2 MB398 downloads562b0a1c9846…Get
  • 2.1.028 Jun 20251.21.6, 1.21.5, 1.21.40.2 MB253 downloads861bb8234ccf…Get
  • 2.0.33 Dec 20241.21.3, 1.21.2, 1.21.1, 1.210.2 MB631 downloads68be0c14d32a…Get
  • 2.0.21 Dec 20241.21.3, 1.21.2, 1.21.1, 1.210.2 MB74 downloadsb05fa4404cae…Get
  • 2.0.121 Nov 20241.21.3, 1.21.2, 1.21.1, 1.210.2 MB88 downloads21af51a12ba6…Get
  • 2.0.019 Nov 20241.21.3, 1.21.2, 1.21.1, 1.210.2 MB78 downloads38aaf9d6270e…Get
  • 1.0.011 Nov 20241.20.6, 1.20.50.2 MB291 downloads92e89ef915ed…Get

Frequently asked

Does Mod Observer work on Minecraft 1.21.11?

Yes. 1.21.11 is the newest Minecraft version Mod Observer declares support for, and the claim comes from the author's own release metadata rather than from a compatibility list somebody maintains by hand.

Which Minecraft versions does Mod Observer support?

Everything the author has declared, from 1.20.2 up to 1.21.11. The full list is in the table above, with the Java runtime each version needs next to it.

Do I need to install Mod Observer on the client or the server?

The client only. There is nothing to install on the server side. That is the author's declared design, not a guarantee for every server: one running anti-cheat or missing a counterpart mod can still object.

Which platform or loader does Mod Observer support?

Fabric. A build for one platform or loader will not necessarily load on another, so this is the first thing to check before the Minecraft version.

Which Java version do I need for Mod Observer?

On the newest Minecraft version it supports, Java 21 or newer. The requirement comes from the Minecraft version you run rather than from the mod itself, so on an older supported Minecraft the answer is that version's Java, not this one.

What licence is Mod Observer under?

MIT, as stated by the author on the platform we synced it from. Check the project's own page before redistributing or bundling it.

How do I install Mod Observer?

Install the matching loader first, then put the downloaded file in your mods folder and start the game. The loader, the mod and Minecraft all have to be on the same version, which is the usual reason a mod does not appear in game.

Where do I download Mod Observer safely?

Start with the author's page on Modrinth, which is where the data here is synced from. MCReference does not host or repackage files. The download link goes to the source recorded for that release; verify the publisher, filename and checksum before running it.

Works on the same versions

Ordered by how much of the recent Minecraft version coverage overlaps, not by popularity.

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Details from Modrinth, where the author last updated it on 22 Dec 2025. We do not host files and we do not republish descriptions; every download link points at the author’s own release.

Is this information wrong or missing something? .