What's Quilt?
Quilt is a fork of Fabric started in 2021, built to be a superset rather than a competitor. The Quilt loader runs almost every Fabric mod out of the box, plus a smaller set of Quilt-only mods that use its own APIs. The goal: keep Fabric compatibility while iterating faster on loader features.
In practice, if you've used Fabric, Quilt feels nearly identical. The community is smaller, so Quilt-exclusive mods are rare, but you don't lose access to the Fabric ecosystem by picking it.
Setting up Quilt
Click the + in GDLauncher, pick your Minecraft version, and choose Quilt. Use the latest stable loader version and create the instance. GDLauncher handles Minecraft, Java, and Quilt itself in the background.
The Quilt equivalent of Fabric API is Quilted Fabric API (QFAPI). It includes Fabric API, so installing it lets you run both Fabric and Quilt mods in the same instance. GDLauncher resolves it as a dependency automatically when you install a mod that needs it.
Adding mods
Open your instance, go to Addons, and use the browser. Filter by Quilt and search for what you want. Fabric mods generally show up too and will load fine on Quilt, but the explicitly-Quilt versions are smoother when available.
Quilt vs Fabric
Same lineage, mostly the same mods. Fabric has the bigger community and is where most mods get released first. Quilt offers some loader-level improvements (better mixin handling, richer mod metadata, more flexible dependency resolution) and runs the Fabric ecosystem on top.
Pick Fabric if you want the mainstream option with the largest active modder base. Pick Quilt if you're curious about its loader features or you're following a modpack that specifically targets Quilt. For most players, the practical difference is small.
OptiFine replacement
OptiFine doesn't work with Quilt either. The same Fabric-side replacements apply: Sodium for performance, Iris for shaders, Continuity for connected textures (so adjacent glass, bookshelves, sandstone, etc. visually merge into one surface instead of showing per-block borders), LambDynamicLights for dynamic lighting (held torches actually light the area around you).
Troubleshooting
Seeing "missing Fabric API" or "missing Quilted Fabric API" errors? Open the instance's Addons tab and check QFAPI is in the list. If it isn't, search for "Quilted Fabric API" and install it manually.
A Fabric mod refusing to load on Quilt is rare but happens, usually with mods that hook into Fabric internals. If swapping to the Quilt-specific version (when one exists) doesn't help, the mod itself may not yet support Quilt.