 GNATS is used by GNU packages and NetBSD.The Apache Software Foundation used the software from 1996-2002, and the Mutt project until 2006.It is also used, or was used in the past, by the FreeBSD Project, OpenBSD, Juniper Networks, Nordic Optical Telescope, CERN, Green Bank Telescope, NRAO AIPS++, European Software Institute, and the BaBar Project at SLAC.