How to add mods to your Minecraft server

Your server has to be on a mod loader first — Fabric, Forge, NeoForge or Quilt. If it is still on Vanilla or Paper, start with How to make a modded Minecraft server, then come back here.

Option 1: install from the panel

The Mods tab has the CurseForge catalogue built in, so for most mods you never have to leave the panel or handle a file. A mod that is only published somewhere else — Modrinth, or the author’s own site — goes in with option 2.

1. Open the Mods tab on the server page.
2. Search for the mod by name.
3. Check the mod lists your Minecraft version and loader — a Fabric mod will not load on Forge, and a 1.20 mod will not load on 1.21.
4. Click Install. The mod is placed in the server’s mods folder.
5. Restart the server so it picks up the new file.

Option 2: upload a jar

For a mod that is not on CurseForge, or a specific build you already have:

1. Download the mod jar for your exact Minecraft and loader version from the author’s page.
2. Open the Files tab and go to the mods folder.
3. Use Upload and select the jar.
4. Restart the server.

Mods or plugins?

Mods and plugins are not interchangeable. Mods (Fabric, Forge, NeoForge, Quilt) change the game itself and can add new blocks, items and mobs — which usually means players need them too. Plugins (Paper, Purpur) only run on the server and work with an unmodified Minecraft client, so anyone can join without installing anything. If all you want is server tools — land claims, homes, an economy — a plugin server is simpler for everyone. Fabric, Forge, NeoForge or Paper? compares them.

Client mods vs server mods

Some mods have to be installed on every player’s Minecraft as well as the server — most content mods that add blocks, items or mobs work this way. Others are server-side only. The mod’s page says which; if it is "required on both", everyone joining needs the same mod and version or they will be disconnected with a message about mismatched or missing mods.

A third kind is client-only: performance and visual mods such as Sodium, Iris or OptiFine-style shaders. They do nothing on a server and some crash it. Install them in your own game, not on the server.

Keeping everyone’s mods in sync

The easiest way to give your friends the right set is to share a list: the mod names and the exact file versions from the server’s mods folder. Better still, build the set as a CurseForge profile or use a published modpack, so everyone installs the same thing in one click — see How to install a modpack.

Updating and removing mods

To update a mod, stop the server, delete the old jar from the mods folder in the Files tab, and install the new one. Do not leave both: two versions of the same mod stop the server from starting with a “duplicate mods” error.

Removing a mod that added blocks or items also removes those blocks and items from the world the next time it loads — they cannot be brought back by reinstalling. Download a copy of the world from the World tab before removing a content mod, in case you change your mind.

Size and mods to avoid

Mod files up to 256 MB can be installed while the server is stopped. Two mods are worth knowing about before you install them:

• spark — the profiler cannot run inside the locked-down container free servers use, and crashes the server at startup.
• World pre-generators and map renderers — useful, but heavy. Run them while nobody is playing and remove or pause them afterwards.

If the server will not start after adding a mod

Open the Console tab and read the first error in the stack trace. The usual causes:

• Wrong version — the mod is built for a different Minecraft version or loader.
• Missing dependency — the mod needs a library mod (often Fabric API, or a specific core mod) that is not installed.
• Client-only mod — it was never meant to run on a server; remove it.
• Two mods conflicting — remove the last one you added and start again to find the pair.

Remove the offending jar from the mods folder in the Files tab and the server will start again. The full list of error messages and what each one means is in Why won’t my Minecraft server start?.