How to Add Mods to a Terraria Server (tModLoader Guide)

To add mods to a Terraria server, you run a tModLoader server instead of the vanilla one, put the mods' .tmod files and an enabled.json list in the server's Mods folder, and restart. Players then join through tModLoader, which offers to download the server's mods for them. This guide shows where to find the mod files, how to set up the server's mod list, what to know about Calamity and RAM, and how to fix the usual sync problems.

Short answer

1. Set up your mods in tModLoader on your own PC and test them in singleplayer.
2. Export the list: Workshop, Mod Packs, Save Enabled as New Mod Pack.
3. Copy the .tmod files and enabled.json into the server's Mods folder.
4. Start the server as a tModLoader server.
5. Friends join through tModLoader and accept the mod download.

Why you need tModLoader

Vanilla Terraria has no mod support, and a vanilla server cannot load mods. tModLoader is the free official modding platform, a separate app on Steam that anyone who owns Terraria can install. Every Workshop mod you know (Calamity, Thorium, Magic Storage, Boss Checklist, Recipe Browser) runs on it.

A modded server has to run the tModLoader server, and players join with tModLoader, not regular Terraria.

Versions in 2026: vanilla Terraria is on 1.4.5, but stable tModLoader is still based on Terraria 1.4.4 while its 1.4.5 port is being developed. Run the latest stable tModLoader on both server and clients, and do not expect a world saved in vanilla 1.4.5 to open in it. More in how to fix Terraria version mismatch.

Step 1: Build and test your mod list

1. Install tModLoader from Steam.
2. Launch it, open Workshop, then Download Mods, and subscribe to the mods you want. Check each mod's page for required dependencies.
3. Open Workshop, then Manage Mods, enable them and click Reload Mods.
4. Create a world and play a few minutes to make sure everything loads without errors.

Testing locally first saves a lot of guessing on the server.

Step 2: Find the mod files

The server needs the actual .tmod files plus a list of which ones are enabled. The easiest way to get both is a mod pack:

1. In tModLoader, go to Workshop, then Mod Packs.
2. Click Save Enabled as New Mod Pack and give it a name.
3. Click Open Mod Pack Folder.

That folder contains a Mods folder with every enabled .tmod file, enabled.json, and an install.txt listing the Workshop IDs.

If you would rather find them by hand, Workshop mods are in your Steam folder under steamapps/workshop/content/1281930/<mod id>/, in a subfolder per tModLoader version, and locally built mods are in Documents\My Games\Terraria\tModLoader\Mods.

enabled.json is a plain list of internal mod names:

[
  "CalamityMod",
  "CalamityModMusic",
  "MagicStorage",
  "BossChecklist",
  "RecipeBrowser"
]

Only mods listed there are loaded, even if more .tmod files sit in the folder.

Step 3: Put the mods on the server

Self hosted: copy the .tmod files and enabled.json into the Mods folder the tModLoader server uses, then start it with start-tModLoaderServer.bat on Windows or ./start-tModLoaderServer.sh on Linux. On Linux, the manage-tModLoaderServer.sh script can also read install.txt and download the Workshop mods for you with its install-mods command.

On GamezServers:

1. Click Backup, then choose tModLoader as the server type in the panel if you have not already.
2. Stop the server.
3. Upload the .tmod files and enabled.json into the server's Mods folder. The Files tab is fine for a few mods. For big lists, get your login from Settings, Show SFTP login, and use FileZilla or WinSCP.
4. Start the server and watch the Console. It lists each mod as it loads.

If the server stops with an error naming a mod, that mod is missing a dependency or is the wrong version. Add the dependency, or remove the mod from enabled.json.

Step 4: How players join

1. Launch tModLoader, not Terraria.
2. Click Multiplayer, then Join via IP, pick a character, and enter the IP and then the port.
3. tModLoader compares mods and offers to download any the player is missing. Accept, and let it reload.

The server's mods are what count. Players can keep extra client side mods, like UI or texture mods, as long as they do not change gameplay.

Calamity and big mod lists: RAM

Terraria is light in vanilla, but content mods add a lot of memory:

Too little memory shows up as long load times, lag during events and crashes. Calamity plus a few quality of life mods is comfortable on 6 GB. See how much RAM a game server needs.

Worlds on modded servers

• New world: the server can create one, or you create it in tModLoader with your mods on and upload it. Some mods add world generation, so worlds made with the mods enabled are best.
• Existing tModLoader world: upload the .wld and matching .twld file together. The .twld holds the modded data. Without it, modded blocks and items are lost.
• Removing a mod: its blocks and items vanish from the world. Back up first.

For uploading, see how to upload a Terraria world to a server.

Common problems

• Players kicked during mod sync: their mod versions differ from the server. Update mods on the server after Workshop updates, and let players resync.
• "You are not using the same version as this server": player and server are on different tModLoader versions. Both should use the latest stable (Steam, Properties, Betas, None).
• Server ignores a mod: it is not in enabled.json, or the internal name is spelled wrong.
• Crash on start after an update: a mod updated and needs a newer dependency, or dropped support for your tModLoader version.
• Joined with regular Terraria: vanilla clients cannot join a tModLoader server.

The easy way

Running tModLoader at home means installing the server, copying mods by hand and keeping your PC on with enough RAM for Calamity. On GamezServers you choose tModLoader in the panel, upload your mod pack through the file manager or SFTP, back up before every change, and move up a plan when your mod list grows. See Terraria server hosting or follow the quick start guide.

FAQ

Can I add mods to a vanilla Terraria server?

No. Vanilla Terraria has no mod support. You need a tModLoader server.

Do my friends need to download the mods themselves?

No. When they join through tModLoader, it offers to download the server's mods for them.

Is tModLoader free?

Yes. It is a free app on Steam for anyone who owns Terraria.

How much RAM does a Calamity server need?

Plan for 4 to 6 GB. 6 GB leaves room for Calamity plus other mods and bigger groups.