How to Install Minecraft Mods on Java Edition

Every Java mod is compiled against one Minecraft version and one mod loader. The loader in turn runs on a particular Java version, which Minecraft dictates. Nothing in the game checks these for you until launch, which is why mods look fine in the folder and still fail.

Read the diagram left to right. Your Minecraft version decides which Java you need and which loader builds exist. Your loader decides which mod files can load at all: a Fabric mod does nothing in a NeoForge instance, and the reverse. And each mod file is built for a narrow band of Minecraft versions; a file for 1.20.1 will not load in 1.21.1, even though the names look similar.

The practical rule that follows: choose your Minecraft version to suit the mods you want, not the other way round. Many large modpacks still target 1.20.1 or 1.21.1, because that is where the mods they depend on are. Opening the mod's page first and reading its supported versions and loaders saves most of the trouble on this page.

Minecraft is sold as two different games. Java Edition runs on Windows, macOS and Linux and is the one with mod loaders and the mods on CurseForge and Modrinth. Bedrock Edition runs on consoles, phones, tablets and Windows, and it cannot run Java mods at all. No loader, converter or patch changes that; Fabric, NeoForge and Forge exist only for Java Edition.

Bedrock has its own system instead: add-ons, made of behaviour packs and resource packs, distributed as .mcpack, .mcaddon or .mcworld files that you import by opening them. Microsoft documents the format on Microsoft Learn. Add-ons change the game through data and scripting rather than by changing the game's code, so the kinds of mods that rebuild Java Edition, such as large tech or performance mods, have no Bedrock equivalent.

To tell which you have, look at the title screen. Bedrock has a Marketplace button; Java Edition has none, and shows its version number, such as 1.21.1 or 26.3, in the bottom-left corner.

This route uses nothing but Mojang's launcher and the loader's installer. It takes about ten minutes the first time. The official launcher downloads the Java version Minecraft needs on its own, which removes one of the four things you have to match.

A mod launcher creates a separate instance for each setup, installs the right loader and Java for it, and lets you search and install mods from inside the app, dependencies included. It is the easiest way to run several modded setups side by side, and it is how most modpacks are played.

The trade-off is that each instance keeps its own game folder, so .minecraft is no longer where your mods, logs or worlds are. Use the launcher's own folder button whenever a guide tells you to open a folder.

You do not choose a loader in the abstract; you choose the one your mods are built for. Still, the three behave differently, and it helps to know which one a mod list points to.

Fabric is lightweight and usually supports new Minecraft versions soon after release. Most performance, utility and client-side mods are on Fabric, and most Fabric mods need the Fabric API library. NeoForge began as a fork of Forge in July 2023 and is where most large content mods for 1.20.2 and newer moved; its versions follow Minecraft's, so NeoForge for 26.x is numbered 26.x. Forge itself is still maintained and holds the large back catalogue for 1.12.2 through 1.20.1, which is why so many long-running packs still use it.

A NeoForge instance does not load Forge mods built for older versions, and Fabric and NeoForge cannot load each other's files. The one bridge, Sinytra Connector, runs Fabric mods on NeoForge in one direction only and is still in beta. Our Forge vs Fabric page compares the two in detail, with live mod counts from Modrinth.

Since Minecraft 26.1 in March 2026, Java Edition needs Java 25. Many guides, videos and forum answers still say Java 21, which is correct only for 1.20.5 through 1.21.11. If you run a 26.x instance on Java 21 it stops at once, and the error tells you so in its own terms: UnsupportedClassVersionError with "class file version 69.0". Subtract 44 from that number to get the Java it wanted.

The official launcher and the CurseForge app handle Java for you. Problems come from third-party launchers pointed at a system-wide Java, from servers, and from the Fabric or NeoForge installer being run with an old Java on the PATH. If an installer will not open, or a server will not start, check which Java it is using first. Our Java version page has a checker and the switch for each launcher.

Download Minecraft mods from CurseForge or Modrinth and nowhere else. They are the platforms mod authors publish on, both let you filter by Minecraft version and loader before you download, and both show the dependencies each file needs. Mirror sites that repackage those files add nothing except risk.

The risk is real. In June 2026 BleepingComputer reported that a malware campaign called WeedHack had infected 116,464 systems since January, according to McAfee telemetry. It spread through fake Minecraft mods, clients, cheats and utilities promoted on YouTube and through poisoned search results, using 3,820 unique malicious JAR files, and it stole Minecraft sessions, browser passwords and cookies, Discord, Steam and Telegram credentials and cryptocurrency wallets. Because a malicious mod is also a .jar, the file type alone does not protect you; the source does.

Mods do not follow Minecraft updates automatically. When a new release such as 26.3 comes out, every mod in your folder needs its own new build for that version, and large mods can take weeks or months to arrive. Until they do, the only safe thing is to stay where you are.

The good news is that a loader profile is tied to one Minecraft version. The official launcher's Latest release entry moves forward when Mojang ships an update; your Fabric or NeoForge profile does not. Problems start when someone switches an existing modded profile or instance to the new version by hand, or copies the old mods folder into a new one, and every mod fails at once.

Worlds are the other half. Minecraft upgrades a world's data the first time a newer version opens it, and it warns you if you try to open a world in an older version than it was last played in, because going backwards can corrupt it. So copy the world folder before you try an update, test the update in a new instance with the new mod builds, and move your world across only once that instance runs.

A crash on launch means the mods were found and something about them is wrong. It is nearly always one of a short list: a mod built for another Minecraft version, a missing library, the wrong Java, or two mods that patch the same part of the game. The launcher's exit code, usually 1, does not tell you which.

The log does. Open the newest file in crash-reports, or logs/latest.log if there is none, and read the last "Caused by:" line; or paste the whole file into the crash analyzer on our crash report page, which runs in your browser and names the likely mod. Fabric writes its dependency errors to latest.log in plain English, such as a mod that "requires … which is missing!". If nothing is named, halve the mods folder and launch again, keeping libraries with the mods that need them.

Memory is the other common case: a large pack that starts fine and dies when a world loads, with java.lang.OutOfMemoryError in the log. Raise the allocation one step rather than giving it everything; our RAM page has a calculator for your own PC and for servers.

Client-side mods, such as shaders, minimaps and performance mods, need to be on your own computer only. Anything that adds blocks, items, mobs or recipes has to be on the server and on every player's game, at the same versions. A mismatch usually shows up as a disconnect with a list of mods that differ.

Java Edition Realms does not support mods. For modded multiplayer you either host a server, on your own PC or a rented one, or share a world through a mod that adds that feature. Our server guide covers putting mods on a server and sorting which ones belong on each side.

Each of the four things that must match has a page with a tool, so you can check rather than guess.