KiCad 8 and newer have built-in importers for Altium schematics, boards, and libraries. See https://docs.kicad.org/9.0/en/kicad/kicad.html#importing_a_project_

KiCad 8 and newer have built-in importers for Altium schematics, boards, and libraries. See https://docs.kicad.org/9.0/en/kicad/kicad.html#importing_a_project_from_another_eda_tool https://docs.kicad.org/9.0/en/kicad/kicad.html#importing_a_p... for more info.