How to install TmodLoader for Terraria

For modded content (Calamity, Thorium, Stars Above, and more), use TModLoader instead of the vanilla server.

Calamity is no longer maintained — checked 18 August 2026

Development of the Calamity Mod ended on 10 August 2026. Its Steam Workshop item is still published and still installs, so existing servers and worlds keep working, but it will not be updated for future Terraria or TModLoader releases. If you run it, pin your Server Version rather than tracking latest (see Maintaining your Terraria server).

Large content mods still in active development: Thorium (last updated 1 August 2026), Fargo's Souls Mod (10 May 2026) and The Stars Above (1 April 2026).

Switching to TModLoader

1. In the Startup tab, set Server Type to tmodloader.

2. Set World Name to a new name (see the warning below).

3. Go to Settings and click Reinstall Server. This swaps the server files; your existing worlds and data stay in place.

4. Start the server. A fresh TModLoader world generates on first boot.

World formats do not mix

TModLoader worlds use their own format: a world made under TModLoader will not load on vanilla or TShock, and your vanilla or TShock world will not load under TModLoader. Give each format its own World Name, and when you switch types, switch the World Name with it. Your other worlds stay safely in worlds/ until you switch back.

The version number is supposed to look old

TModLoader intentionally runs on an older Terraria version than vanilla and TShock (the console banner shows both, for example Terraria Server v1.4.4.9 - tModLoader v2026.5.3.0). This is not your server being outdated: players join with the TModLoader client, which runs on that same base version automatically, so everything matches on their end.

Installing the tModLoader client

TModLoader is not a setting inside Terraria. It is a separate app on Steam, it is free, and it requires you to own Terraria. It installs alongside vanilla instead of replacing it, so both stay in your library and both stay playable.

1. Search Steam for tModLoader and install it.

2. Launch it once. It uses its own save folder — Documents\My Games\Terraria\tModLoader on Windows — so your vanilla worlds and characters are untouched.

3. Get the server's mods: from the main menu use Workshop → Download Mods, or subscribe on the tModLoader Workshop at steamcommunity.com/app/1281930/workshop/. Subscribed mods download to steamapps\workshop\content\1281930, which is where the .tmod files in the next section come from.

4. Turn them on under Workshop → Manage Mods, then click back to reload.

The two clients do not mix

TModLoader will not connect to a vanilla Terraria server, and a vanilla Terraria client will not connect to your TModLoader server. Treat them as two separate games. If your server runs a legacy build, players have to match it: right-click tModLoader in Steam, then Properties → Betas, and pick the same branch.

Installing Mods

1. Subscribe to the mods on the Steam Workshop.

2. Copy the .tmod files from your local TModLoader Workshop folder (path varies; check the current TModLoader docs).

3. Upload the .tmod files to tmodloader/Mods/ via SFTP.

4. Enable them in tmodloader/Mods/enabled.json:

   [
     "ThoriumMod",
     "StarsAbove",
     "CalamityMod"
   ]
   

5. Restart.

Most overhaul mods are client-required. Players install them through their own TModLoader client and the Steam Workshop. Mismatched mod lists are the top cause of join failures, so publish your required list.

What to Read Next

• Maintaining your Terraria server and back up before any mod change
• TShock Setup if you want moderation tools alongside mods
• Terraria Server Commands for the console commands that still apply under TModLoader

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