PREREQUISITES

Make sure you've installed a JDK first.

Installing IntelliJ IDEA

If you do not have IntelliJ IDEA installed, you can download it from the official website - follow the installation steps for your operating system.

The Community edition of IntelliJ IDEA is free and open-source, and it is the recommended version for modding with Fabric.

You may have to scroll down to find the Community edition download link - it looks like the following:

Installing "Minecraft Development" Plugin

The Minecraft Development plugin provides support for modding with Fabric, and it is the most important plugin to install.

TIP

Although this plugin isn't strictly necessary, it can make modding with Fabric much easier - you should consider installing it.

You can install it by opening IntelliJ IDEA, and then navigating to File > Settings > Plugins > Marketplace tab, then search for Minecraft Development in the search bar, and click the Install button.

Alternatively, you can download it from the plugin page and then install it by navigating to File > Settings > Plugins > Install Plugin From Disk.