Minecraft mods vs plugins vs data packs

A plugin changes the server and runs only there, so your players need nothing extra. A mod changes the game itself, and many mods must also be installed by every player. A data pack is a third kind that changes the game through the world’s own files. A normal server runs plugins or mods, not both, and your server software decides which.

The three kinds

	Plugin	Mod	Data pack
Runs on	Paper, Purpur and other servers built on Paper	Fabric, Forge or NeoForge	Any Java server
Where the files go	`plugins`	`mods`	the `datapacks` folder of the world
File	a `.jar`	a `.jar`	a folder or a `.zip`
Do players install it?	No	Usually yes, check the mod’s page	See the pack’s page

Paper’s documentation describes plugins as the way to extend Paper beyond its configuration files: you put the .jar in the plugins folder and restart. It also warns that a plugin gets full access to your server and the machine it runs on, so only install plugins from sources you trust.

A mod goes in the mods folder, and it has to be built for your loader (the server program that loads mods: Fabric, Forge or NeoForge) and your Minecraft version. Fabric’s documentation says a mod made for one Minecraft version might not work on the next, and that a Fabric mod is not for another loader.

A data pack is a folder or a .zip file with a pack.mcmeta file in it, the Minecraft Wiki says. It goes in the datapacks folder of the world.

Do players need it?

Plugins: Paper’s guide has you install a plugin only on the server. Players join with a normal game.
Mods: read the mod’s page on Modrinth or CurseForge. It says whether the mod is needed on the client, the server or both. If the client side is required, every player installs the same mod, on the same loader and Minecraft version, or they cannot join. A mod that is only for the client, such as Sodium, goes on the players’ computers and not on the server.
Data packs: they are loaded by the server. Read the pack’s page to see if players need anything else.

See install a mod for the steps.

Why one server cannot run both

A plugin needs a server built on Paper, and a mod needs Fabric, Forge or NeoForge. They are different server programs, and they load add-ons in different ways. The panel shows it on the Versions page: “Plugins run on Paper and its forks, mods on Fabric, Forge and NeoForge.” If you move a server from Paper to Fabric, the plugins in the plugins folder stay on disk but do not load.

A hybrid tries to load both. Plugin authors say this does not work well. The panel’s software list marks a few hybrids “Runs mods and plugins”. Two examples: EssentialsX says it is built for the Bukkit API, which “does not properly support mods”, and Floodgate’s wiki says there is no way to run it on a server that mixes Forge and Bukkit or Fabric and Bukkit. Choose one kind.

Tell which kind a file is

A .jar is a zip file, so you can open it with an archive program and look for one file:

File inside the jar	Kind
`plugin.yml`	A plugin for Paper-based servers
`fabric.mod.json`	A Fabric mod
`META-INF/mods.toml`	A Forge mod
`META-INF/neoforge.mods.toml`	A NeoForge mod

Paper’s documentation says plugin.yml holds a plugin’s name, version, commands and permissions. Fabric’s wiki says a mod must have fabric.mod.json at the root of the jar to load. The Forge and NeoForge documentation name mods.toml and neoforge.mods.toml under META-INF. A data pack has a pack.mcmeta file and is not a .jar.

The download page also tells you. Modrinth and CurseForge list the loader (Paper, Fabric, Forge, NeoForge) or the file type for each version.

In the ArthOS panel

Open your server and choose Add-ons. The header names your software and the kinds it takes, for example “Purpur 26.3” and “plugins and data packs”. The buttons are:

Plugins, on Paper-based software.
Mods, on Fabric, Forge, NeoForge and Quilt.
Data packs, on every Java server.
Modpacks, for a whole pack of mods at once. Each pack needs its own loader and Minecraft version, for example NeoForge on Minecraft 1.21.1. You do not have to set that up: the panel replaces the server software for you, and its plan shows what will change before you confirm. See install a modpack.
Versions, to change the software.

Not checked on 26.3 as of 11 October 2026: the Mods button, which was read from the panel’s code. On a Purpur 26.3 server the live panel showed Plugins, Data packs, Modpacks and Versions.

You only see Plugins or Mods, never both, because they follow your server software. If the panel cannot tell which one you run, it offers only Data packs and asks you to start the server once. To change the software, use the Versions button: see switch to Fabric, Forge or NeoForge and switch to Paper or Purpur.

If it does not work

I do not see a Mods button. Your server runs Paper or Purpur. Mods need Fabric, Forge or NeoForge.
I do not see a Plugins button. Your server runs a mod loader. Plugins need Paper or Purpur.
I put a plugin in mods, or a mod in plugins, and nothing happens. Each folder is read by one kind of server. Move the file to the right folder, or get the build made for your software.
I want both a mod and a plugin. Choose one kind of server. Data packs work on either.