The schematic and 3D libraries supported by KiCad team.

The footprint libraries are the *.pretty repos themselves and are used online by default. If you want to download them locally, the library-repos-install.bat and library-repos-install.sh scripts in the KiCad source can do this automatically.

For more information, please check: https://kicad-pcb.org/contribute/librarians/

Please, check the CONTRIBUTING.md file.