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Aternos: how to install mods and plugins

Aternos supports Bukkit/Spigot/Paper-style plugins as well as full mods on Forge and Fabric, but never both at once. Picking the architecture closes off some options for good, so before the first click on "Install" it helps to know what you are actually installing. This guide shows how plugins differ from mods, how to add them step by step, and which packs are really worth enabling on free hosting.

The difference: plugins (Bukkit/Spigot/Paper) vs mods (Forge/Fabric)

At first glance plugins and mods do the same thing: they add features to a server. Underneath they are two completely different worlds, and mixing them up is the most common source of frustration for new admins.

Plugins: server-side extensions

Plugins run on the server only. They use the Bukkit API (and its forks: Spigot, Paper, Purpur), which intercepts game events such as a player joining, a block breaking or a command being typed, and lets you write reactions to them. Because plugins do not touch the client code, players do not have to install anything on their side. They join with plain Minecraft and everything works.

The price of that convenience: plugins cannot add new blocks or mechanics that do not exist in vanilla. You can modify existing behavior, add commands and build minigames out of existing blocks, but new mobs, new dimensions or new technology are out of their reach.

Mods: changes on both the client and the server

Mods dig into the game's own code. Forge and Fabric are mod loaders that load the modifications together with Minecraft, and players have to do the same on their side. Every mod that adds a new block, mob or recipe must be installed on the server AND for every player. The versions must be identical, including the versions of helper libraries.

In return you get everything. RLCraft with its new survival systems, All the Mods with dozens of tech mods, Pixelmon with its Pokémon: all of these are mods, not plugins. Organizationally, though, it is a lot more work.

Quick comparison

  • Server engine - Paper/Spigot/Bukkit for plugins, Forge/Fabric for mods. No engine does both
  • Client side - plugins: nothing required, mods: a full install for every player
  • Scope of changes - plugins modify behavior, mods add entirely new content
  • Versioning - plugins: loose, a newer Paper usually works with older plugins; mods: strict, the wrong version means a crash
  • Performance on Aternos - plugins on Paper run light, mods on Forge can eat all the RAM you are given

How to install a plugin on Aternos (Bukkit-based)

You can add plugins only when the server engine is Paper, Spigot or CraftBukkit. If the server runs on Vanilla, Forge or Fabric, first change the software in the Software tab, then come back to install the plugin.

Installing from the Aternos library

  1. Log in to the panel and open your server
  2. In the side menu choose Plugins
  3. Type the plugin name in the search box (for example "EssentialsX")
  4. Click Install next to the version that matches your Paper
  5. Restart the server and the plugin loads on startup

Aternos searches Bukkit.org, SpigotMC and Hangar (Paper), so you will find most well-known plugins without leaving the panel. Some premium plugins (for example paid ones on SpigotMC) are not available, so you have to upload them by hand.

Uploading a .jar file by hand

If a plugin is not in the Aternos library (premium, brand new, specialized), download the .jar file from the author's official page and upload it yourself:

  1. Download the plugin's .jar file from SpigotMC, Modrinth or Hangar
  2. In the Aternos panel open the Files tab
  3. Go to the /plugins folder
  4. Click Upload and pick the downloaded .jar file
  5. Restart the server

After the restart the plugin creates its own folder in /plugins/PluginName/ with configuration files. You edit them in the same Files tab.

Note: Every plugin uses memory and CPU. On Aternos with 2-4 GB of RAM the realistic ceiling is 10-15 plugins at a time. Above that the server starts to lag no matter how many players are online. Start with EssentialsX + LuckPerms + CoreProtect and let the rest depend on your specific project.

How to set up a server with mods (Forge/Fabric) on Aternos

A modded server needs a completely different engine. In the Aternos panel you change Software to Forge, NeoForge or Fabric, choose the Minecraft version, and only then do you see the Mods tab.

Installing individual mods

  1. Make sure the server is Forge/NeoForge (Forge mods) or Fabric (Fabric mods). These two ecosystems are NOT compatible
  2. Open the Mods tab
  3. Search for the mod by name. Aternos searches CurseForge and Modrinth
  4. Click Install and wait for Aternos to download the JAR
  5. Repeat for every mod you want to add
  6. Restart the server

After startup the server reports in the console how many mods loaded and which ones failed. If a crash report appears, the most common cause is a missing required library (for example Fabric API for Fabric, or Cloth Config for most configurable Fabric mods).

Installing mods for your players

Every player needs the identical mod pack installed locally. The quickest route is a launcher that helps with this:

  • Prism Launcher - free and open source, imports packs from CurseForge and Modrinth
  • CurseForge App - the official CurseForge launcher, downloads whole modpacks in one click
  • Modrinth App - a modern alternative, great for packs from Modrinth

The official Minecraft Launcher handles individual mods, but importing a whole pack means copying files by hand. For a group of more than 3 people, take a few minutes to teach everyone to use Prism or the CurseForge App.

Ready-made modpacks in one click

Instead of putting a pack together yourself, pick a ready-made modpack from the Aternos library when you create the server. Aternos offers hundreds of CurseForge packs with the mods and dependencies already configured. Your friends only need to install the same pack on their side (through the CurseForge App, or Prism Launcher with a CurseForge import).

Popular plugins (EssentialsX, WorldEdit, LuckPerms, Vault)

To start, a handful of plugins is enough, the ones without which most servers make little sense. This is the list we recommend to every new Aternos admin.

EssentialsX

The absolute standard. It adds the commands /home, /warp, /tpa, /kit, /pay, /nick and hundreds more. Without EssentialsX a survival server is practically unplayable: with no teleport to your home or to friends, every trip turns into an hour-long trek. EssentialsX consists of several modules (EssentialsX Chat, EssentialsX Spawn, EssentialsX Protect), so install at least the core.

LuckPerms

The best rank and permission system in the Bukkit ecosystem. You define groups (Player, VIP, Moderator, Admin), assign them permissions (essentials.tpa, worldedit.*) and add players to the groups. LuckPerms has a web editor that lets you configure ranks from the browser, which is especially handy for more elaborate structures.

WorldEdit

Mass terrain editing with commands: you select a region with two clicks, then use //set stone, //replace grass dirt, //copy, //paste. Essential when building cities, mockups and scenery for PvP servers. On Aternos it is worth lowering the operation limit in the config (limits.max-blocks-changed.default) so a player cannot hang the server with a command that changes millions of blocks.

Vault

An intermediary library that many economy and permission plugins use. It does nothing by itself, but plugins such as Essentials Economy, ShopGUIPlus and ChestShop need it to work. Install it right away to avoid dependency errors when you add an economy later.

CoreProtect

Logs every player action: who placed what, who broke what, who opened a chest. The /co rollback command undoes griefing with a single command. On publicly open servers CoreProtect is what guarantees you will not lose months of work to one troll.

Geyser + Floodgate

A bridge that connects Bedrock Edition players (phones, consoles, Windows 10/11) to a Java server. Geyser translates the protocol, and Floodgate handles authentication so Bedrock players can join without owning Java Edition. That way Java and Bedrock users play together on one server.

You will find the full list of plugins with detailed descriptions in our Minecraft plugin catalog.

Popular modpacks (RLCraft, Better MC, FTB)

If you prefer ready-made packs to putting mods together yourself, here are the most popular modpacks that Aternos has in its library. All of them are free, and you only pay if your 2-4 GB RAM allotment turns out not to be enough to run them.

RLCraft

Extreme survival. RLCraft adds hardcore mechanics such as thirst, temperature and realistic damage. It is not a pack for everyone: the difficulty can put off players used to vanilla. On Aternos it needs a solid 4 GB of RAM and a view-distance reduced to 4-5.

Better Minecraft

A vanilla extension that keeps the feel of the original. It adds hundreds of mobs, biomes, blocks and systems (Create, Farmer's Delight, Alex's Mobs) but does not change the foundations of the game as aggressively as RLCraft. For a group of friends looking for "vanilla plus" it is the best choice. It needs 4-6 GB of RAM, which on Aternos runs right at the limit.

SkyFactory 4

Skyblock with heavy automation. You start on a single tree in the void and build an entire technological civilization. The pack is relatively light on memory: 3-4 GB is enough for 4-6 players.

All the Mods 9 (ATM9)

ATM9 packs more than 300 mods (tech, magic, exploration, decoration) into one pack. For fans of giant farms and automated factories it is paradise. For your Aternos server it is a challenge. It needs at least 6 GB of RAM, which usually exceeds the limit of the free plan.

FTB modpacks (Feed The Beast)

A series of classic modpacks: FTB Revelation, FTB Academy, FTB OceanBlock. FTB bets on a balanced stack of tech mods: less of the magic chaos of ATM9, more focused progression. Most packs fit in 3-5 GB of RAM, which suits Aternos.

Pixelmon

Pokémon in Minecraft. You catch, train and battle. Pixelmon has elaborate turn-based battle mechanics, a PokéMart system, gyms and an Elite Four. A medium-weight pack: 3-4 GB of RAM is enough for 3-5 players on Aternos.

Tip: For every modpack, check the minimum RAM requirements on its CurseForge page. If they are 6+ GB, Aternos probably will not be enough. In that case consider moving to cheap paid hosting with guaranteed RAM: 4 GB dedicated is worth more than 4 GB shared.

FAQ: common questions about mods and plugins on Aternos

Is there a limit on the number of plugins or mods on Aternos?

Aternos does not set a hard limit on the number of files, but the available RAM (usually 2-4 GB) does limit you. In practice a safe ceiling is 10-15 plugins at a time or a modpack of up to 150 mods. Above that the server starts to lag, and an OutOfMemoryError can appear on startup no matter how well optimized each individual plugin is.

How do I update plugins on Aternos?

In the Plugins tab each plugin shows its current and the latest available version. Click Update to download the newer one: Aternos swaps the JAR file and loads the new version on the next restart. Plugins you uploaded by hand have to be updated yourself: download the new JAR from the author's page, delete the old one from /plugins in the Files tab and upload the new one.

Can I run plugins and mods on the same Aternos server?

Not in the classic sense, because each engine handles only one kind of extension. There are hybrids such as Mohist (Forge + Bukkit) or Arclight that let you run Bukkit plugins together with Forge mods. Aternos supports Mohist for selected versions. A warning: such hybrids tend to be unstable, crash more and have less community support than plain Paper or plain Forge.

Does every player have to download the mods if my Aternos server is modded?

Yes, every player needs the identical mod pack installed locally. The versions of the mods, the mod loader (Forge or Fabric) and Minecraft must be the same on both sides. The most convenient way is a launcher such as the CurseForge App, Modrinth App or Prism Launcher, which keep the mod packs in sync between the server and the clients.

Can I use paid SpigotMC plugins on Aternos?

Yes, if you own a license. Download the .jar file from your SpigotMC purchases, upload it by hand through the Files tab into the /plugins folder and restart the server. Keep in mind that the Aternos terms forbid commercial use of the server: you can run paid plugins, but you cannot sell ranks or items to players.

Why does a mod install but not work after the server starts?

The most common cause is a missing dependency. Fabric mods almost always need Fabric API, and configurable Fabric mods also need Cloth Config. In the Forge ecosystem many mods require libraries such as GeckoLib or Curios API. Check the mod's CurseForge page: the "Required Dependencies" section shows what you have to add.

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