GDB, the GNU Project debugger, allows you to see what is going on `inside' another program while it executes - or what another program was doing at the moment it crashed.

GDB can do four main kinds of things (plus other things in support of these) to help you catch bugs in the act:

The program being debugged can be written in Ada, C, C++, Objective-C, Pascal (and many other languages).

Those programs might be executing on the same machine as GDB (native) or on another machine (remote). GDB can run on most popular UNIX and Microsoft Windows variants.

GnuPG is the GNU project's complete and free implementation of the OpenPGP standard as defined by RFC4880. GnuPG allows to encrypt and sign your data and communication, features a versatile key management system as well as access modules for all kinds of public key directories. GnuPG, also known as GPG, is a command line tool with features for easy integration with other applications. A wealth of frontend applications and libraries are available. Version 2 of GnuPG also provides support for S/MIME.

GnuPG is Free Software (meaning that it respects your freedom). It can be freely used, modified and distributed under the terms of the GNU General Public License .

GnuPG comes in two flavours: 1.4.16 is the well known and portable standalone version, whereas 2.0.22 is the enhanced and somewhat harder to build version.

Project Gpg4win provides a Windows version of GnuPG. It is nicely integrated into an installer and features several frontends as well as English and German manuals.

Project GPGTools provides a Mac OS X version of GnuPG. It is nicely integrated into an installer and features all required tools.

Project Aegypten developed the S/MIME functionality in GnuPG 2.