Bitstream Vera Fonts clone with a wider range of characters

https://dejavu-fonts.github.io/

Couple of command line utilities for working with desktop entries

https://www.freedesktop.org/wiki/Software/desktop-file-utils/

8086 development tools

http://homepage.ntlworld.com/robert.debath/

AMD and Intel CPUs microcode updates

AMD CPUs microcode updates

Intel CPU microcode updates

https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files

Developer help browser for GNOME 3

http://www.imendio.com/projects/devhelp/

Tool to effectively maintain todo lists aimed at developers

http://swapoff.org/devtodo.html

Wonderful Sega Genesis/MegaDrive emulator

http://dgen.sourceforge.net/

KAME DHCP6 client, server, and relay

http://wide-dhcpv6.sourceforge.net/

Decode and diagnose sniffed DHCP packets

http://www.mavetju.org/unix/general.php

Disk Information Utility

https://diskinfo-di.sourceforge.io/

Diagram creation program, similar to Visio

https://live.gnome.org/Dia

Console Interface to configure ports

https://bitbucket.org/m1cro/d4p/

Console Interface to configure ports

https://bitbucket.org/m1cro/d4p/

Simple english/german dictionary

http://www.de.freebsd.org/~wosch/dict/dict.cgi

Dict protocol (RFC 2229) server

http://www.dict.org/

GNU diff utilities

http://www.gnu.org/software/diffutils/diffutils.html

Monospace bitmap font, primarily aimed at programmers

http://www.donationcoder.com/Software/Jibz/Dina/

Open source video codec from the BBC

http://dirac.sourceforge.net/

Graphical diff tool

http://freecode.com/projects/dirdiff/

Client for managing and downloading certificate revocation lists

http://www.gnupg.org/aegypten2

Frontend to xgamma

http://gnu.ethz.ch/linuks.mine.nu/displaycalibrator/

Distribute compilation of C(++) code acrosss machines on a network

http://distcc.org

Extremely fast library for floating-point convolution

http://cr.yp.to/djbfft.html

DjVu base libraries and utilities

http://djvu.sourceforge.net/

FTP benchmark program

http://www.kegel.com/dkftpbench/

Another hyper make utility

http://code.google.com/a/apache-extras.org/p/dmake/

Portable debug memory allocation library

http://dmalloc.com/

X11 menu application designed for the dwm window manager

https://tools.suckless.org/dmenu

Tool for dumping DMI (SMBIOS) contents in human-readable format

https://www.nongnu.org/dmidecode/

Distributed.net distributed computing project client

http://www.distributed.net/

Lightweight DNS forwarder, DHCP, and TFTP server

http://www.thekelleys.org.uk/dnsmasq/doc.html

Simple sudo alternative to run commands as another user

https://github.com/slicer69/doas/

Meta-port for the different versions of the DocBook DTD

http://www.oasis-open.org/docbook/

DocBook SGML DTD

http://www.oasis-open.org/docbook/

DocBook SGML DTD into nroff/troff -man macros converter

https://www.oasis-open.org/docbook/tools/dtm/

Generates various output formats from DocBook SGML documents

http://sources.redhat.com/docbook-tools/

DocBook XML DTD

https://www.oasis-open.org/docbook/

DocBook W3C XML Schema

https://www.oasis-open.org/docbook/xmlschema/1.0b1/

XSL DocBook stylesheets

http://docbook.sourceforge.net/projects/xsl/

Namespace-aware DocBook XSLT stylesheets

http://docbook.sourceforge.net

Emacs lisp modules for editing DocBook documents

http://nwalsh.com/emacs/docbookide/

DOCSIS(tm) binary configuration file encoder/decoder

https://github.com/rlaager/docsis

Command-line DNS client

https://dns.lookup.dog/

DNS-over-HTTP server proxy

https://github.com/jedisct1/rust-doh

Doom data files (Doom, Doom II, Hexen, Heretic and Strife)

Complete Doom-based game IWAD that is Free Software

http://freedoom.sf.net/

Improved and extended version of Doom

http://doomlegacy.sourceforge.net/

Emulator of a PC with DOS

http://dosbox.sourceforge.net/