Edit tModLoader Mod Config on Your Server

Most big tModLoader mods keep their options in a config: boss health, drop rates, difficulty scaling and the like. On your server those settings live in small JSON files. The Mods tab installs and switches mods but doesn't edit their options, so you change them in the File Manager. This guide shows where the files go, two ways to make them and what to do when a change doesn't stick.

Checked against tModLoader v2026.08.3.0 (stable, built on Terraria 1.4.4), October 2026.

Before you start

• Run tModLoader. The Mods tab only appears for it. The Server software card on the Startup tab switches you over, and Add tModLoader mods to your Terraria server installs the mods.
• Know which options belong on the server. Every mod config is either a Server Side Config or a Client Side Config. A server side config is shared by all players and kept by the server, so a file on your server is what counts. A client side config is personal, such as a display option, and each player sets theirs in their own game.

How the files are named

Each config is one file named <ModName>_<ConfigName>.json, kept in a folder called ModConfigs. The file only needs the values you want to change. Anything it leaves out stays at the mod's default, and with no file at all the mod runs on its defaults. So a fresh server may have no config files yet.

On your server the folder is saves/ModConfigs, because the server starts with its save directory set to saves. A new server only has saves/Worlds. tModLoader's source creates ModConfigs when a config is saved, which on a server happens when a connected player applies a config change. Open File Manager, then the saves folder. If ModConfigs isn't there, create it.

Make the file on your PC

This is the easy way, because tModLoader writes the file with the right name and the right setting names.

1. Install the same mods in tModLoader on your PC.
2. In tModLoader's Mods menu, find the mod and press its config button, which has the tooltip Click to open config. Change what you want in the Server Side Config, then press Save Config.
3. On Windows the saved file is in Documents\My Games\Terraria\tModLoader\ModConfigs.
4. Stop the server from the Console tab.
5. In File Manager, open saves/ModConfigs and upload the .json file.
6. Start the server. The mod reads its config as it loads.

Edit the file on the server

If the file is already on the server, click it in File Manager and edit it in place. A file looks like this, with a made-up setting name:

{
  "BossHealthMultiplier": 2
}

The setting names and values are the mod's own, so check its Workshop page for what each one does. Keep the quotes and the commas between lines as they are in the file. Save, then restart the server.

Make sure the change took

• Your option didn't change. Check the file name is spelled exactly like the mod and config names, with the underscore between them. A file with the wrong name is not read.
• The file disappeared. It couldn't be read, so tModLoader removed it. Upload your saved copy and fix the typo.
• It only changed for you. The setting is a Client Side Config. Players set those in their own game.