GL Tubing and Extrusion Library

https://linas.org/gle/

OpenGL Extension Wrangler Library

http://glew.sourceforge.net/

Some useful routines of C programming (previous stable version)

http://www.gtk.org/

Some useful routines of C programming (current stable version)

https://www.gtk.org/

Programming reference for devel/glib20

https://www.gtk.org/

C++ interfaces for glib2

https://www.gtkmm.org/

Text search engine

http://webglimpse.org/

GLX extension headers

http://www.freedesktop.org/wiki/Software/xlibs

GNU version of 'make' utility

https://www.gnu.org/software/make/

A generic matrix template library

http://home.gna.org/getfem/

Free library for arbitrary precision arithmetic

https://gmplib.org/

GNATS, the GNU Problem Report Management System

https://www.gnu.org/software/gnats/

Simple network library built upon Glib-2

http://www.gnetlibrary.org/

Programming reference for x11/gnome-desktop

http://www.gnome.org/

GNOME JavaScript common modules and tests

Common startup and shutdown subroutines used by GNOME scripts

The game of Go

https://www.gnu.org/software/gnugo/

GNU grep

http://www.gnu.org/software/grep/

Complete and free PGP implementation

https://www.gnupg.org/

The GNU Privacy Guard

https://www.gnupg.org/

GNUstep makefile package

http://www.gnustep.org/

GNU Transport Layer Security library

https://gnutls.org/

Generate interface introspection data for GObject libraries

https://gi.readthedocs.io/en/latest/

Explore, Search and Discover

http://earth.google.com/

Fast, multi-threaded malloc() and nifty performance analysis tools

https://github.com/gperftools/gperftools

Script to analyze web server and generate Google Sitemap files

http://code.google.com/p/sitemap-generators/

Visual effects library

http://sourceforge.net/projects/goom

Commandline text rendering utility - creates images from text

http://linuxbrit.co.uk/gozer/

Generates perfect hash functions for sets of keywords

https://www.gnu.org/software/gperf/

Library to make access to GnuPG easier

http://www.gnupg.org/related_software/gpgme/

Daemon that monitors one or more GPSes attached to a host computer

https://gpsd.gitlab.io/gpsd/index.html

GNU stream editor

https://www.gnu.org/software/sed/sed.html

Collection of globally shared GSetting schemas

Standard fonts for Ghostscript

http://www.cs.wisc.edu/~ghost/doc/gnu/index.htm

The GNU Scientific Library - mathematical libs

http://www.gnu.org/software/gsl

Audio converter and library for converting u-law to gsm encoding

http://kbs.cs.tu-berlin.de/~jutta/toast.html

Gimp Toolkit for X11 GUI (previous stable version)

http://www.gtk.org/

C++ wrapper for gtk, a x11 graphics library

Interactive typing tutor

http://www.gnu.org/software/gtypist/

Compression utility designed to be a replacement for compress

http://www.gnu.org/software/gzip/

gzip recovery toolkit

https://www.urbanophile.com/arenn/hacking/gzrt/

Anti-spam / denial of service counter-measure tool

http://www.hashcash.org/

High-color icon theme shell from the FreeDesktop project

http://www.freedesktop.org/Standards/icon-theme-spec

Utility primarily designed to find the owner of an IP block

Network auditing tool

http://www.hping.org/

Hebrew spellchecker and morphology engine

http://hspell.ivrix.org.il

All W3C published SGML DTDs for HTML

Converts HTML documents into plain text

http://www.mbayer.de/html2text/

Time synchronization over http utility

http://www.vervest.org/htp/

Tool for measuring webserver performance

https://github.com/httperf/httperf