Fabric, Quilt and Forge are mod loaders for Minecraft Java Edition. They let the game load mods, but a mod made for one loader won't necessarily work with another. If you've already picked a modpack, the choice is usually made for you: install the loader and Minecraft version that its author lists.
When you're putting a pack together yourself, start with the mods you want to use. Each download needs to match both your loader and your Minecraft version. For example, a file labelled Fabric for Minecraft 1.20.1 isn't a replacement for the Forge version of that mod, even though the game version is the same. A download labelled NeoForge has its own requirements too; don't assume it's interchangeable with Forge.
Forge
Forge has been around for years, so you'll come across it in plenty of modpacks, particularly when returning to an older pack. Use the Forge release the pack specifies rather than installing whichever version you find first. The mods were put together for that setup, and changing the loader version can leave you with a pack that won't start.
Fabric
Fabric has its own selection of mods, from performance changes to larger additions to the game. You'll sometimes see it described as the choice for small or lightweight packs, but that doesn't tell you whether it supports the particular mods you want.
One extra download to watch for is Fabric API, which many Fabric mods need. Installing Fabric Loader doesn't install that library for you. When a mod lists Fabric API as a dependency, download the matching version and add it alongside the mod. The Fabric installation guide explains how to check these requirements.
Quilt
Quilt started as a fork of Fabric, which is why Quilt Loader can run many Fabric mods. There are exceptions, and compatibility doesn't automatically work the other way round: a Quilt-only mod may not run on Fabric. Quilt also doesn't load Forge or NeoForge mods.
For an existing Quilt pack, keep the loader and libraries its author specifies. Quilt Standard Libraries was discontinued in December 2025, although the older releases remain available. The Quilt FAQ covers this in more detail.
Before switching an existing server to another loader, back up its world and configuration files. Removing mods can also remove the blocks and items they added to your save, so this isn't just a case of changing the server type and carrying on.
