How to Mod Terraria: Install tModLoader, Add Mods and Play With Friends (2026)

Here's how to mod Terraria on PC: you install tModLoader, a free app on Steam that sits next to your normal game, then add mods from inside it. You need to own Terraria already. That's the whole trick: tModLoader shows up in your Steam library as its own game, you launch it instead of vanilla Terraria, and the Workshop menu on the title screen is where mods come from. Everything below is the detail, plus the gotchas that eat people's evenings.

It's a PC thing: Steam lists tModLoader for Windows, macOS and Linux, and the Terraria wiki's modding page covers the desktop version only. As of November 2026, the stable tModLoader is built on Terraria 1.4.4 content. It also updates monthly, which matters more than it sounds (more on that below).

What you need

• Terraria, owned legitimately. tModLoader won't work with a pirated copy.
• A PC. Windows, Mac or Linux/SteamOS. Steam lists a 6 GB RAM minimum on Windows (16 GB recommended), and big mods eat more.
• Steam, even if you bought Terraria on GOG (see below).

Before you start, back up your Terraria saves. The wiki warns that mods can corrupt or delete save data. In practice tModLoader keeps its own saves anyway, but a copy costs you nothing.

How to install tModLoader on Steam

1. With Terraria in your Steam library, search the Steam store for tModLoader and install it. It's free.
2. Find it in your library. It's listed as a separate game from Terraria, so your vanilla install stays untouched.
3. Launch tModLoader, not Terraria, whenever you want to play modded.

On Linux or Steam Deck, don't run it through Proton. tModLoader runs as a native Linux app, so set Compatibility to None. If you use a family-shared copy of Terraria, tModLoader won't launch normally. You'll need the manual install route below, launched with the start-tModLoaderFamilyShare script, and Steam multiplayer won't work that way (joining by IP still does).

Uninstalling is just as easy: right-click tModLoader in Steam, Manage, Uninstall. Vanilla Terraria isn't affected.

Installing tModLoader without Steam (GOG and manual)

Bought Terraria on GOG? You can still mod it, it's just a manual install:

1. Download tModLoader.zip from the tModLoader releases page on GitHub.
2. Unzip it into a folder called tModLoader next to your Terraria folder (GOG usually installs to C:\GOG Games). Don't dump the files straight into the Terraria folder.
3. If the zip has an extra Build folder inside, move its contents up a level.
4. Run start-tModLoader.bat. On Linux or Mac, make the .sh files executable first with chmod +x.

You repeat those steps for every update, which is a pain. And you should still install Steam, because the in-game mod browser uses it to reach the Workshop. The tModLoader FAQ says Steam needs to be installed and running for GOG players to download or update mods. Without Steam, tModLoader still runs, but you'd be dropping .tmod files in by hand.

How to add mods to Terraria

tModLoader mods live on the Steam Workshop, and there's also a mod browser built into the game, so you don't have to open Steam's website at all. From the title screen, head into the Workshop menu and use Download Mods to find and install what you want. You can also browse them on the tModLoader Steam Workshop page.

Then comes the step people forget: open the Mods menu, enable what you downloaded, and reload. Mods don't apply until the reload finishes.

What to try first? The big ones people reach for:

• Calamity: a huge content mod. The Terraria wiki sums it up as a mod that adds lore, new items, weapons, armor, biomes, town NPCs and a lot of post-Moon Lord content.
• Thorium: reads like unofficial DLC. It adds three new classes (Bard, Healer, Thrower), a new biome under the ocean called the Aquatic Depths, bosses and thousands of items.
• Fargo's mods: Fargo's Mutant Mod is a quality-of-life mod aimed at cutting grinding.
• Magic Storage and AlchemistNPC: two quality-of-life picks listed on the Terraria wiki.

Search the Workshop for any of them and check it's been updated recently. Mods come and go.

You can save your enabled list as a mod pack from the Workshop menu, which makes switching setups painless. A mod collection always grabs the latest versions, while a mod pack stays frozen.

Your saves are separate (this is why people panic)

Open tModLoader for the first time and your characters and worlds are gone. They aren't. tModLoader doesn't use vanilla's save files. It keeps its own in Documents\My Games\Terraria\tModLoader, while vanilla stays in Documents\My Games\Terraria.

The in-game menu can copy your vanilla characters and worlds across, and your vanilla files aren't changed when it does. Going the other way is the risk: take a modded character or world back to vanilla and the modded items and tiles are lost. If you use Steam Cloud, turn it off for those files before migrating. The cloud space is shared with Terraria.

Playing modded Terraria with friends

Everyone has to be running tModLoader. Steam's own page says it plainly: vanilla players can't join tModLoader players. And since the mods change the game itself, you'll want everyone running the same mod list, so sort that out together before you hit Join. tModLoader supports Steam multiplayer and joining by IP.

Make sure multiplayer works in plain Terraria first. If it doesn't there, it won't magically work modded.

Want a dedicated modded server? tModLoader installs its own server start scripts (start-tModLoaderServer.bat or .sh). The default port is 7777 and the default player cap is 8. The world has to be the .wld file, not .twld. Friends outside your network need port forwarding. My Terraria server hosting guide walks through the hosting side, and tModLoader's wiki has a page on starting a modded server (partly out of date for 1.4.4, so read it with that in mind). If you're also wondering who can join what, is Terraria cross-platform? covers the vanilla answer.

Is tModLoader legal? Is it safe?

Yes, it's legal. It's an official Steam app, co-published by Re-Logic (the Terraria developer) and the tModLoader team, and the Terraria wiki says Re-Logic officially endorses it. It's not a hack or a crack. You just have to own the game.

The mods themselves are a different story. They're made by the community, and neither Re-Logic nor the wiki tests them. Stick to the in-game browser and Steam Workshop. Random .tmod files from sketchy sites are the part I'd skip. The tModLoader FAQ flags manually installed mods (they show up purple in the Mods menu) and suggests swapping them for the Workshop version.

Keeping mods working after updates

tModLoader 1.4 updates every month, and a mod that worked yesterday can break after an update because the author hasn't caught up. Errors like a JITException, or a message saying a mod was built for a different tModLoader version, usually mean the mod is out of date. Disable it until it's updated.

If the game crashes or won't load at all:

• Hold Shift while tModLoader starts to skip loading mods.
• Disable everything, then turn mods back on in batches to find the culprit.
• Check the log at Documents\My Games\Terraria\tModLoader\Logs\client.log.
• Running out of memory? Cut the biggest mods or play on Small or Medium worlds. The tModLoader settings can show a memory estimate per mod.

Two other launch-day villains: antivirus or Windows Controlled Folder Access blocking saves, and a OneDrive-synced Documents folder throwing cloud errors. Both are covered in the FAQ.

You can also run an older or preview build from Steam: right-click tModLoader, Properties, Betas. The default branch is stable, and there are legacy branches for older Terraria versions. Preview is for modders and testers and can break your mods.

What about console and mobile?

tModLoader is a PC app: Windows, Mac and Linux. If you're on console or phone, this isn't your route, and I wouldn't go hunting for modded installers on random download sites.

Want to make your own mods?

Mods are written in C#, and you'll need the .NET SDK. The tModLoader GitHub wiki has a guide for developers and a beginner modding guide, and the Terraria Community Forums have a long-running modding tutorial series. Start there. It's a whole project of its own.

Where to go next

Modded or not, a lot of Terraria's best challenge runs are about the world you start in. Try the Terraria one-block challenge, or build an island start with the Terraria skyblock seed guide. And if you've gotten the modding itch and want to see what else is out there, games like Terraria is my roundup.