Guides
How to Install Mods on a Minecraft Server (Forge, Fabric & Modpacks)
Step-by-step: install a full modpack or add individual mods to a Forge or Fabric server. Covers mod loaders, file upload, client vs server-side mods, and the most common errors.
Adding mods to a Minecraft server comes down to two paths: installing a full modpack through your host's control panel, or manually uploading individual mod files via FTP. Both are straightforward once you understand what a mod loader is and which mods need to be on both sides. This guide covers both methods for Forge, Fabric, and NeoForge servers.
Quick overview
- To install a modpack — use your host's one-click installer (CurseForge / Modrinth). Everything is set up for you.
- To add individual mods — install the matching mod loader (Forge or Fabric), then upload
.jarfiles to themods/folder. - Client and server must match — same mod loader version, same mod versions for shared mods.
Step 1: Choose Your Mod Loader
Mods are built for a specific mod loader. You can't mix them — a Fabric mod won't load on a Forge server and vice versa. Pick the loader based on the mods or modpack you want to run.
If you're running a specific modpack, it will tell you which loader and Minecraft version to use. For choosing between Forge-based and Fabric-based server software, see our server software comparison guide.
Method 1: Installing a Full Modpack (Easiest)
If you're running a known modpack (ATM10, Vault Hunters, RLCraft, etc.), the fastest way is a one-click modpack installer. Most control panels support CurseForge and Modrinth packs directly — no manual file handling needed.
How to install a modpack via control panel
- Create a new server in your host's panel — select "Modpack" or "CurseForge" as the server type
- Search for the modpack by name (e.g. "All The Mods 10" or "Vault Hunters 3")
- Select the version you want — match this to what your players are using
- Let the installer run — it downloads the mod loader, all mods, and default configs automatically
- Start the server and check the console for errors before players join
Your players then install the same modpack version on their client via CurseForge, Prism Launcher, or Modrinth App. The versions must match — a server running ATM10 v2.8 won't accept a client on v2.7.
Method 2: Installing Individual Mods Manually
If you're building a custom modpack or adding specific mods to an existing server, you install mods manually as .jar files. The process is the same for Forge, NeoForge, and Fabric.
2a. Install the mod loader on your server
First, your server needs to run Forge, Fabric, or NeoForge instead of vanilla. In your host's panel, change the server type from "Vanilla" to the loader you need and select the version. The panel will install the loader automatically. If your host requires manual installation, download the installer from files.minecraftforge.net (Forge), fabricmc.net (Fabric), or neoforged.net (NeoForge) and run it locally to generate the server .jar, then upload that.
2b. Download the mod .jar files
Download mods from CurseForge or Modrinth — these are the two trusted sources. When downloading:
- Match the Minecraft version (e.g. 1.20.1, 1.18.2)
- Match the mod loader (Forge, Fabric, NeoForge)
- Check mod dependencies — many mods require a library mod like Cloth Config or Architectury to also be installed
2c. Upload mods to your server
Stop your server first. Upload the .jar files to the mods/ folder in your server directory. Use your host's file manager or connect via FTP/SFTP with a client like FileZilla. The folder structure should look like:
server/
mods/
create-1.20.1-forge.jar
jei-1.20.1-forge.jar
cloth-config-forge.jar
server.properties
world/
2d. Start the server and check the console
Start the server and watch the console. Forge and Fabric print each mod it's loading — you'll see lines like Loading mod: Create 0.5.1. If a mod fails to load, the console will say why (missing dependency, wrong version, etc.). Fix errors before players connect.
Client-Side vs Server-Side Mods
Not every mod needs to be on both the server and the client. Getting this wrong is one of the most common causes of connection errors when players try to join.
Server + Client required
Most gameplay mods — new blocks, items, mobs, dimensions
- Create, Tinkers' Construct
- Biomes O' Plenty
- Any mod adding new content
Server-side only
Performance and admin mods that don't add visible content
- Spark (profiler)
- Lithium, Starlight
- LuckPerms, EssentialsX
Client-side only
Visual and UI mods — not installed on server at all
- Sodium, OptiFine
- JEI (client features)
- Minimap mods
A mod's CurseForge or Modrinth page will list whether it's required on server, client, or both. When in doubt — if the mod adds blocks, items, or changes gameplay — it goes on both sides.
Common Errors and How to Fix Them
"You don't have the required mods" on join
The client is missing mods that are on the server (or vice versa). Match the mod list exactly. Every mod that adds content must be installed on both sides at the same version.
"Mod file [x] needs language [forge] to be loaded first"
You uploaded a Forge mod to a Fabric server (or vice versa). Check the mod page — it will list which loader it supports. Delete it and download the correct version.
Server crashes on startup with "missing dependency"
The mod requires another mod (a library) that isn't installed. The error will name the missing mod. Download that dependency and add it to the mods/ folder too.
"This mod is not compatible with Minecraft version X"
The mod version doesn't match your server's Minecraft version. Go back to the mod's download page and select the version that matches your server (e.g. 1.20.1 vs 1.21).
Server starts but no mods load
The mods/ folder doesn't exist yet, or your server is still running vanilla. Confirm the server type is set to Forge or Fabric — not vanilla. The mods/ folder is created when the mod loader first starts.
How Much RAM Do Modded Servers Need?
Every mod you add increases RAM and CPU usage. A rough guide:
- 1–10 mods (light): 2–4 GB RAM, ~200–260% CPU
- 10–100 mods (medium): 4–8 GB RAM, ~300% CPU
- 100–200 mods (heavy modpack): 8–12 GB RAM, ~400% CPU
- 200+ mods (mega packs like ATM10): 12–16 GB RAM, ~450–500% CPU
For detailed breakdowns by specific modpack, see our guides on ATM10, Vault Hunters, RLCraft, and modded server RAM in general.
Install Mods on a Minecraft Server — FAQ
Do players need to install the same mods as the server?
For any mod that adds blocks, items, or gameplay changes — yes, both sides need the same mod at the same version. Server-only mods (performance, admin tools) and client-only mods (visual, UI) are exceptions.
Can I add mods to a server that already has a world?
Yes, with caveats. Adding mods that generate new biomes or structures won't affect already-generated chunks — new content only appears in newly explored areas. Adding mods that remove existing content can corrupt blocks in the world. Always back up before adding mods to an active server.
Can I use Forge and Fabric mods on the same server?
No. Forge and Fabric are separate mod loaders and are not compatible. Some mods publish separate builds for each loader — you download the one matching your server. You can't mix them on the same server instance.
Can I add mods to a Paper or Spigot server?
Paper and Spigot run plugins, not mods. They use a different system — plugins go in the plugins/ folder, not mods/, and players don't need to install anything client-side. If you want Forge or Fabric mods, you need to switch server type.
Where do I download mods safely?
CurseForge (curseforge.com) and Modrinth (modrinth.com) are the two trusted sources. Avoid random download sites — they often host outdated versions, modified jars, or malware disguised as mods.
Skip the setup — install any modpack in one click
BiomeHosting supports one-click CurseForge and Modrinth modpack installation. Pick your pack, choose a version, and the panel handles the rest. View plans and get your modded server running today.