ModsFinder

Mod Observer

by Sn0wix

With Mod Observer installed on a server, joining players are checked against the list of mods the server allows.

FabricClient required, server optionalMIT LicenseOpen source1.20.2 – 1.21.11

What it does

When a player joins a server that runs Mod Observer, the mod reads the set of mods loaded on the client and compares it with the list the server owner has configured. Mods the server does not allow can be refused, and the player receives a kick message explaining why the connection was closed. Only the client side needs the mod, so the server can run without it. Mod Observer requires Fabric API and is published for Fabric across 17 release versions, 1.20.2 – 1.21.11, under the MIT License.

Key features

  1. Loaded mod check

    On join, the mod lists the other mods loaded on the client and checks them against the server's rules.

  2. Server-side allow list

    Server owners decide which mods a player may run, and the check on join applies that decision.

  3. Kick message on mismatch

    A player whose mods fail the check is disconnected with a message stating the reason.

Compatibility

Latest build for each game version and loader.

1.21.x12 of 12 versions with builds
1.21.113.0.2
1.21.103.0.2
1.21.93.0.2
1.21.83.0.2
1.21.73.0.2
1.21.62.1.3
1.21.52.1.3
1.21.42.1.3
1.21.32.1.3
1.21.22.1.3
1.21.12.1.3
1.212.1.3
1.20.x5 of 5 versions with builds
ReleaseBetaAlphaNot available

Only full game releases are shown. This mod publishes no snapshot builds.

Requirements

Dependencies declared by the latest file for each loader.

Required 1

Fabric APILightweight and modular API providing common hooks and intercompatibility measures utilized by mods using the Fabric toolchain.
Required

Optional 1

Mod MenuAdds a mod menu to view the list of mods you have installed.
Optional

Questions

Does Mod Observer need Fabric API?

Yes. Fabric API is a required dependency, so it must be installed alongside Mod Observer on the Fabric loader.

Does the server have to run Mod Observer?

No. The mod is needed in the player's game, and the server may leave it out.

In the catalog

Mod Observer is one of 5,392 Social mods on ModsFinder, and one of 4,084 Social mods for Fabric. 19,862 mods support Minecraft 1.21.11.

Social mods5,392Fabric modsMods for 1.21.1119,862

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What the author says

ModObserver, as the name suggests, observes, which mods are loaded, and upon joining a server, sends those mods to the server. The server owner can adjust, which mods are allowed and which are not.
Sn0wix, on the Modrinth page

Official listing

Owner
Sn0wix
Published
2024-04-02
Updated on Modrinth
2025-12-22
Facts verified
2026-10-15

Tags

ManagementSocial
Open on ModrinthCompare