Mods change or add to Minecraft: Java Edition, and they need a mod loader to start the game with them. There are three main loaders: Fabric, NeoForge and Forge. This guide covers the steps every loader shares; each loader's page has its download and its own installation steps.

Pick the loader your mods need

A mod only runs on the loader it was made for, so start from the mods you want. Open each mod's page on Modrinth or CurseForge and check two things: the loaders it lists and the Minecraft versions it supports. Choose the loader most of your mods share: one installation runs one loader.

Loader	Known for	Download and install
Fabric	Lightweight and quick to update; home of Sodium and Iris. Most of its mods need Fabric API.	Fabric page
NeoForge	Fork of Forge since 2023, with many large content mods on recent versions.	NeoForge page
Forge	The oldest loader, behind most classic mods and older modpacks.	Forge page

Install the loader

Each loader has an official installer that adds a new installation to the Minecraft Launcher. The loader pages above give the exact build for each Minecraft version, the official download and the steps. Two points apply to all of them:

Close the Minecraft Launcher before you run an installer.
The installers are .jar files that need Java on your computer. Only Fabric offers a Windows .exe that uses the launcher's own Java.

After installing, start the new installation once. This first start creates the mods folder.

Download mods from trusted sources

Get mods from Modrinth or CurseForge, or from the author's own page. Those sites check uploads and let you report a file. Sites that re-upload mods are a common source of malware. A mod is always a .jar file: never run an .exe that claims to be a mod.

On the mod page, download the file that matches both your Minecraft version and your loader. The Blockaria mods catalog lists the loaders and versions of each mod and links to the official files only.

Put the mods in the mods folder

System	Default mods folder
Windows	%appdata%\.minecraft\mods
macOS	~/Library/Application Support/minecraft/mods
Linux	~/.minecraft/mods

If your installation uses its own game directory, the mods folder is inside that folder. The folder icon next to the installation in the Installations tab opens it.

Drop the .jar files in as you downloaded them. Do not unzip them.
Add a few mods at a time and start the game in between: a problem is then easy to trace.
Back up your worlds before you add, remove or update mods. Blocks and items from a removed mod disappear from the world.

Check versions and dependencies

Each mod file has to match three things: your Minecraft version, your loader and its dependencies. A dependency is another mod it needs to run, often a library. The mod page lists the required ones: install them in the version it asks for. On Fabric, the usual one is Fabric API.

Fix the common errors

Problem	Cause and fix
The loader says a file is for another loader	A Fabric file in a NeoForge or Forge installation, or the reverse. Download the file made for your loader.
A mod requires another mod	Missing dependency. Install the mod it names, in the version shown.
A mod requires another Minecraft version	The file is made for another version. Download the one for your version.
A mod is present in several files	Two versions of the same mod. Delete the older one.
Crash while loading or in game	Open logs/latest.log or the newest file in crash-reports in the game directory. Lines starting with "Caused by" usually name the mod. Remove the last mod you added, or move half of the mods out to find the culprit.
Freezes or out of memory	Large modpacks need more memory: how to allocate more RAM.
The installer does not open	Java is missing, or .jar files open with another program. Install Java, or run java -jar followed by the file name in a terminal.

Modpacks and servers

The Minecraft Launcher cannot install modpacks. For a ready-made pack, use the CurseForge app or the Modrinth App: they install the right Minecraft version, loader and mods for you.

To play with mods on a server, the server needs the same loader and the same content mods. Client-only mods, such as performance or interface mods, stay on the players' computers. For the server itself, see how to run a Minecraft Java server.

FAQ

Can I mix Fabric and NeoForge mods?

No. One installation runs one loader, and each mod file is made for one loader. Many popular mods publish a file for each loader: pick the one that matches yours.

Are Minecraft mods safe?

Mods from Modrinth and CurseForge are checked by those sites and can be reported. Avoid sites that re-upload mods: they are a common source of malware. A mod is a .jar file, never an .exe.

Do mods work on Bedrock Edition?

No. Mods and mod loaders are for Java Edition only. Bedrock Edition uses add-ons instead.

Do I have to reinstall mods after a Minecraft update?

Yes, in most cases. Install the loader for the new version, then download the file of each mod made for it. Keep the old installation until all your mods are updated.