The source code and binaries are released under MPL 2.0.
The folder icon asset is made by FatCow (http://fatcow.com/free-icons) and licensed under CC BY 3.0 US.
In order to setup a workspace to play around with the source code, first clone this repository using your Git client (make sure to select the correct branch, they are named by Minecraft versions; master is always the latest work in progress version).
Once you cloned the repository, import the Forge or Fabric project into your development environment. You may need to run gradlew genIntellijRuns
or gradlew genEclipseRuns
if there are no run configurations after importing the project.