When you create a new project in Foundry, the first decision is your mod loader: Fabric or NeoForge. Both are fully supported - this guide explains what each one is and how to choose.
What Is a Mod Loader?
A mod loader sits between your mod and Minecraft, providing APIs and hooks your code uses to add items, blocks, mobs, and mechanics to the game. Your mod targets a specific loader - a Fabric mod doesn't run on NeoForge and vice versa.
Fabric
Fabric is a lightweight, modular mod loader. Its core API is intentionally small - it provides the minimum needed to load mods and interact with Minecraft, with additional functionality available through separately maintained libraries (like Fabric API).
In practice:
- Clean, well-documented API
- Historically fast to update when new Minecraft versions release
- Favored by mods that prioritize performance and low overhead
- Uses Minecraft's internals more directly, which means mods can do more - but can also break more on MC updates
NeoForge
NeoForge is the modern successor to Forge, the original major Minecraft mod loader. It was forked from Forge in 2023 and has since replaced it as the maintained option for the Forge-style ecosystem.
In practice:
- Larger built-in API surface - more hooks, events, and capabilities included
- Large existing catalog of mods from Forge's many years as the dominant loader
- Natural migration path if you're porting an existing Forge mod
- More abstraction between your code and Minecraft internals
Key Differences
| Fabric | NeoForge | |
|---|---|---|
| API philosophy | Minimal core, opt-in libraries | Comprehensive built-in API |
| Ecosystem origin | Independent | Successor to Forge |
| Version updates | Typically faster | Typically slightly later |
| Mod compatibility | Fabric mods only | NeoForge/Forge mods only |
| Porting old Forge mods | Requires rewrite | Mostly straightforward |
The two ecosystems are separate. A mod built for Fabric won't run on NeoForge and vice versa, so if you plan to support a specific mod as a dependency, make sure you're on the same loader.
Which Should You Pick?
Pick NeoForge if:
- You're migrating a Forge mod
- You want to build a mod that works alongside the large NeoForge mod catalog
- You prefer a comprehensive built-in API with less reliance on external libraries
Pick Fabric if:
- You want to target the latest Minecraft version as quickly as possible
- You're building a mod that benefits from Fabric's lightweight approach
- The mods you want to depend on or complement are on Fabric
If you're building something new with no existing constraints, either works. The day-to-day modding experience in Foundry is the same for both - same project setup, same AI capabilities, same build loop. The choice matters for ecosystem compatibility (which other mods your users can run alongside yours) more than for the development experience itself.
In Foundry
Both loaders are supported across all current Minecraft 1.21.x and 1.20.x versions. NeoForge is selected by default in project creation, but you can switch to Fabric with a single click. Once you've created a project, your mod loader is set - to switch, you'd start a new project.
If you already have a NeoForge or Fabric mod you want to port to a new Minecraft version, Foundry's AI handles the API differences between versions automatically, including NeoForge's Gradle configuration changes between 1.20.x and 1.21.x.
Download Foundry and start with whichever loader your project calls for.