How to Set Up a Modded Terraria (tModLoader) Server

Hosting a modded Terraria world means running the right kind of server and getting your mods to load on it. This guide covers the three server types, how to install mods, and the two gotchas that trip everyone up: 64-bit memory and branch matching.

Vanilla vs tModLoader vs TShock

There are three server flavors, and picking the right one matters:

• Vanilla server runs the base game only. It cannot load mods, so it is not an option for a modded world.
• tModLoader server is the official modding server. This is what you need to run Calamity, Thorium, and other tModLoader mods.
• TShock is a server built for administration: permissions, commands, anti-grief, plugins, and player management. Modern TShock builds run on top of tModLoader for modded-plus-admin setups, but if you just want mods and friends, plain tModLoader is simpler.

For most groups: use tModLoader. Add TShock only if you need heavy moderation tools.

Installing mods on the server

There are two common ways to get mods onto a tModLoader server:

1. Steam Workshop / Mod Browser. The easiest path. Subscribe to mods in the tModLoader Mod Browser (in-game) or via the Steam Workshop, then enable them. On a dedicated server you point it at an enabled-mods list so it downloads the same set.

2. Manual .tmod files. Every mod compiles to a .tmod file stored in your Mods folder:

Terraria/tModLoader/Mods/ Calamity.tmod ThoriumMod.tmod MagicStorage.tmod enabled.json

The enabled.json file lists which mods are turned on. Copy your .tmod files and enabled.json to the server's Mods folder and restart.

A typical enabled.json looks like:

[ "CalamityMod", "ThoriumMod", "MagicStorage", "RecipeBrowser" ]

Use 64-bit for Calamity

The modern tModLoader is 64-bit, and you must use it for large content mods. Calamity, Thorium, and The Stars Above can exceed the memory ceiling of old 32-bit builds and crash with out-of-memory errors. If your host or install is 32-bit, switch to the current 64-bit tModLoader before adding heavy packs. This is the number-one cause of modded Terraria server crashes.

Match the branch

tModLoader has release branches (the current stable, plus legacy branches like 1.4.3-legacy for older mods). The server, every client, and every mod must be on the same branch and version. If the server is on the latest tModLoader but a player is on a legacy branch, they cannot connect, or mods will refuse to load.

Checklist:

1. Decide on a branch (usually the latest stable).
2. Ensure every player sets tModLoader to that branch in Steam's beta properties.
3. Ensure every mod version supports that branch.
4. Keep the server on the identical version.

Clients must match the server

Just like the version, the mod list must match. Everyone connecting needs the same enabled mods. tModLoader helps by offering to download the server's mods on join, but it is smoother if everyone subscribes to the pack in advance so the join is quick and nobody is stuck downloading a gigabyte of Calamity assets on the loading screen.

Server config basics

tModLoader dedicated servers read a serverconfig.txt file where you set the world name, port, max players, and password. A minimal example:

worldname=CalamityWorld maxplayers=8 port=7777 password=optional autocreate=2

Point the server at your world file, open the port on your firewall, and you are online. On a hosted panel these fields are exposed as simple form inputs.

The easy way

Standing up a tModLoader server, wiring enabled.json, and keeping 64-bit memory happy is a lot of manual work. Nxeon's Terraria server hosting runs tModLoader out of the box with a one-click Mods manager, correct 64-bit memory allocation, and branch selection, so you skip the config entirely.

Grab a server from our game servers, install your pack, match your branch, and invite your friends into a fully modded Terraria world.