This is the simplified version! For technical answers, see the "expert mode" supplement.

For most cases, the answer is “snapshot 18w43b and above, releases 1.14 and above”.

There exist ways to run Fabric with older versions - modded or vanilla, but they're currently non-trivial - see the expert FAQ for more details.

A few modpacks are currently being distributed via MultiMC exports, such as All of Fabric, and some are also available on CurseForge. Don't bother with the Launchpacks - they are generally “proof of concept” and not intended for production gameplay.

As of November 2021, the following launchers are available for this:

• Official Launcher - an installer is available on Fabric's download page.
• Xbox Game Pass Launcher - the Fabric installer supports this launcher with 0.9.0 and above, but the launcher itself may not behave correctly.
• MultiMC - a guide is available here for windows, and here for macOS; there is an “Install Fabric” button to easily install Fabric loader.
• CurseForge - supports Fabric, just choose “Fabric” then select a version when creating a modpack.
• GDLauncher - supports Fabric, just choose “Fabric” then select a version when creating an instance.
• ATLauncher - downloads are available on Fabric's download page.
• HMCL - supports Fabric download and installation, including sources from mirror websites.

Please keep in mind that Fabric API is a separate component and must be downloaded separately - you can find it here.

We recommend MultiMC due to its superior user experience for modded environments.

As of 30th June 2019, the following launchers are available for this:

• MCUpdater - guide
• Technic (Solder) - guide
• ATLauncher - guide
• MultiMC/Vanilla - you can always export a modpack or use a ZIP file!
• GDLauncher - Right click on an instance and click “Export Instance”.

Not at the moment. This may change by the end of the year, but is unlikely to be officially supported.

• Fabric does not currently work on top of Forge on modern Minecraft versions.
• It is theoretically possible to create a way to do so - that is to say, there are no known major technical obstacles in accomplishing such.
• There were some experiments and discussions done in this regard (as of 30th June), but nothing usable by end users or mod developers.

The development team does not consider Forge interoperability a high-priority goal, as our focus in our limited time dedicated to the project is on supporting the Fabric community and its developers and users.

Consider using an OptiFine alternative, as unofficial mods such as OptiFabric may not be compatible with your mods.

OptiFine alternatives on Fabric

The future of Optifabric and recommended alternatives

Fabric's rendering patches, while as minimally invasive as possible, make some assumptions about the data format used internally by the vanilla rendering system. Shaders break this assumption, so things go awry. Workarounds do exist and are implemented by the most recent versions of said unofficial mods.

DO NOT downgrade Fabric API as a workaround for this. It's a bad idea.

Not at the moment. Sponge does not yet have a ready API or a working implementation for 1.14, the Minecraft version that Fabric runs on.