GridKa is the German Tier-1, located at Karlsruhe Institute of Technology (KIT), formerly known as Forschungszentrum Karlsruhe (FZK).
It supports all four WLCG VOs - Alice, ATLAS, CMS and LHCb - as well as some smaller non-LHC VOs. Other big services hosted by GridKa provided to WLCG include the GGUS help desk and the GridKa-CA.