How do I install mods?

Installing mods on your server is quick with the Mods tab — but first your server has to be running a mod loader. Here's the full flow.

Prerequisites

Mods only run on Forge or Fabric — not on Vanilla or Paper. Set your loader in the Versions tab first if you haven't already.

Make sure you're on Forge or Fabric (set it in the Versions tab first — mods don't run on Vanilla/Paper).
Open the Mods tab, search for a mod, and install — the panel drops it into your mods folder.
Restart the server.
Every player must have the same mods on their own client to join.

Warning: Mixing mods for the wrong loader or MC version causes crashes — match your Forge/Fabric version.

Why doesn't the Mods tab work on my server? Because you're not on a mod loader — switch to Forge or Fabric in the Versions tab first.

Do my players need the mods too? Yes — every player must have the same mods on their own client to join.