GNU GNATS is a set of tools for tracking bugs reported by users to a central site. It allows problem report management and communication with users via various means. GNATS stores all the information about problem reports in its databases and provides tools for querying, editing, and maintenance of the databases. Thanks to its architecture, GNATS is not bound to a single user interface – it can be used via command line, e-mail, Emacs, or a network daemon, usually used with a Web interface. Together with the fact that all GNATS databases and configuration can be stored in plain text files, it allows easy use and provides good flexibility. Basically, if the GNATS tools do not provide everything you need, you can add your own additional utilities using standard GNU tools. The newest GNATS release is 4.0. This is the first official release to incorporate major advances including multiple database support, customized fields and comprehensive WWW and Tk based front-ends. These features were first seen in the 4.0 beta releases Before 4.0 the latest official release was 3.113.1. A security vulnerability has been found in the 3.113.1 release. There are no plans to fix this problem, all GNATS users should upgrade to 4.0. Several third-party interfaces and other tools that work with GNATS have been contributed, the most actively developed are Gnatsweb, a web-based interface, and TkGnats, a Tcl/Tk-based interface for UNIX/Linux and Windows, which can be found in the contrib subdirectory of the GNATS distribution. Releases of these tools aren’t necessarily synchronized with GNATS releases, see the section on downloading below for details on how to get the newest version.