Adding mods, plugins and modpacks to a Minecraft server

Two different jobs get filed under the same word. Adding LuckPerms to a Paper server and installing All the Mods on a fresh Forge server both feel like "adding mods", and on uniz.host you can do both on the same server. This walks through each, which server software accepts which, and the one behaviour that surprises everyone — saving mods does not restart your server.

A pack, your own mods, or both

Open a Minecraft server and you get a Content tab. Inside it is a row of sections: the first is Mods — or Plugins, if your software runs plugins — followed by Data packs, Resource pack and Worlds. There is nothing to switch on first: the tab shows the sections your server can actually use, and you add to whichever one you need.

A server created as a modpack gets a pack field at the top showing the pack it is running, and below it the same list everyone else has, for the mods you add yourself. The two are not alternatives — a pack brings its own mods and your list sits on top of them. Every other Java software gets the list alone, because a pack carries its own loader and would fight the software you already chose. A modpack server changes packs by picking a different one in that field; it does not detach from packs entirely.

Bedrock servers get neither, so their Content tab has no mods section at all — a section a server cannot use is not shown. Bedrock's own equivalent is add-ons, and those live in the Add-ons section of the same Content tab.

Which software takes mods, which takes plugins

This is the part that costs people an evening. "Mod" and "plugin" are not two words for the same file, and a file built for one loader will not load on the other.

In plain words: a Forge mod cannot load on Paper, and a Paper plugin cannot load on Forge. The two hybrids are the exception — they carry a Forge loader and a Bukkit plugin layer in the same server, which is why their Content tab has a Mods section and a separate Plugins section.

Vanilla is the only Java software with no loader, so it is the only one with no mods or plugins section on the Content tab at all. That refusal is enforced on the server side too, not just hidden in the page. Two beta softwares, Pumpkin and Custom, sit outside the picker groups as well and behave the same way.

The software is fixed at creation, but not forever: the version-and-software section on the Settings tab can move a server between those thirteen Java softwares. Crossing a family line — say Fabric to Paper — makes every installed file meaningless, so that dialog warns you and makes you tick an acknowledgement that your installed mods will be removed.

CurseForge or Modrinth

Both catalogues are supported, and the choice is per mod, not per server. Press the add button and the Add content dialog asks which catalogue to browse first — Modrinth, marked Recommended, or CurseForge — then Next opens the search, where you can still switch between the Modrinth and CurseForge tabs; whatever you pick from there is remembered on that entry alone. A list can hold CurseForge mods and Modrinth mods at the same time, and each row shows where it came from.

That also means nothing is cleared when you browse the other catalogue — an entry carries its own platform, so the list you already built is untouched. A modpack is the one exception: a pack reference belongs to one catalogue and cannot be re-read by the other, so changing the pack means choosing a whole new one.

CurseForge depends on a platform API key, and the search page says plainly that CurseForge may be unavailable if that key is not configured — Modrinth needs no key.

Hybrid servers do not get the choice at all. Mohist and Arclight put mods and plugins into one list, and only Modrinth can express both in a single list, so their mods section shows a line saying hybrids install via Modrinth only, and the add button skips the catalogue step and goes straight to the search. Proxies (Velocity) are Modrinth-only for the same kind of reason: the proxy image reads no CurseForge files at all.

Adding individual mods, step by step

Open the Content tab at its mods section

Go to your server and open the Content tab; it opens on the Mods (or Plugins) section. The Add mods (or Add plugins) button is at the top right — there is no setup to choose first. You need the Content permission — server owners have it, team members only if you granted it; without it you can read the list, but the add button does not appear and the switches in the table are disabled.

Add each mod, choosing its catalogue as you go

Press the add button, pick Modrinth or CurseForge in the Add content dialog, press Next, and the search opens in place of the table. Search, click, done — each pick is added with its newest version that is compatible with this server's software and Minecraft version, so an incompatible pin is not something you can create by accident. If nothing compatible exists, you get told rather than given a broken entry.

Each pick becomes a row in the tab's table, with the version that got pinned. The version itself is the control: click it and the version picker opens, so you can move that row to another build. The row's switch turns that mod off for a while without removing it, and the remove button asks Remove (mod name)? before dropping the row entirely. A row reading "Always latest" is Not pinned to any build: the server picks the newest compatible one on every boot, so updates arrive on their own and the result is not fixed. You can choose that deliberately in the version dialog, and older entries created before version pinning existed sit in the same state. If you already know the project name, the small "add by project name (slug)" toggle opens a plain input.

Every change saves at once while your players keep playing

The mods section has no save button: every add, removal, switch and version pick is saved the moment you make it, and nothing on your server moves. The bar above the table says what just changed, followed by "takes effect after the next restart". This is deliberate — you can prepare a mod change in the middle of a busy evening and let people play on.

Restart when the server is empty

Because the save only rewrites the template your next pod boots from, your running server is still on the old list. While the server is running, a banner on the server page says changes are pending a restart. Hit Restart now on the bar above the table, or Restart in the server's header, when your players are offline and the new list is downloaded on the way up.

Installing a modpack instead

On a server created as a modpack, the Modpack field in the mods section shows the pack in use now, and clicking it asks for a catalogue first, with CurseForge marked recommended because that is where most packs live, then opens the pack search. Picking a different pack opens a Change the modpack to (pack name)? confirmation that lists what was set for the old pack and will be cleared; nothing changes until you press Change pack.

Two limits are worth planning around. The RAM warning quotes 4GB, and it is a recommendation, not a gate: a smaller plan saves fine and simply risks crashing while the pack loads. And on CurseForge, a pack whose author has disabled third-party downloads is rejected when you switch to it, rather than being accepted and then crash-looping forever with a stuck server.

Expect the first boot to be slow. A big pack downloads everything, builds its loader and generates a world before it can answer a health check, so a booting server is given a 20-minute window before anything treats it as failed — a budget sized after a real pack got killed mid-install on a vanilla-sized one. Watch the console tab while it happens; logs stream while the server is still starting.

Where the files land, and what a pack locks

Everything lives on one volume mounted at /data, which is exactly what the Files tab shows you. Your mods sit in a mods folder (plugins in plugins) next to world at the top level — which is why a world reset can wipe the world and leave your installed files alone, and why uploading a jar by hand into that folder is a real option for anything the catalogues do not carry.

The one thing a modpack takes away is version freedom. A modpack server cannot change its Minecraft version or its software at all — the version section on the Settings tab shows a note telling you to detach the pack first, and the API refuses the request. Detaching does not actually buy it back: the server type stays a modpack type, which is outside the switchable set, so the change is refused for a second reason. If you need a different version, build a new server on the pack build you want.

Read next

• Minecraft server hosting — the softwares, and what running one yourself involves
• Minecraft server.properties — the values on the Settings tab, with the same restart rule
• Java runtime — when a pack needs a specific JVM version
• Server RAM — how much a modded server actually needs
• Dashboard tour — reading the tabs, badges and usage charts