GNU M4

https://www.gnu.org/software/m4/m4.html

Bonjour (zero-configuration networking) by Apple

https://developer.apple.com/bonjour/

Apple mDNS responder - BSD nsswitch module

https://developer.apple.com/bonjour/

Madplay MP3 player (part of MAD project)

https://www.underbit.com/products/mad/

Command-line make-like build tool using Go as input files

https://magefile.org/

Magus runtime utilities for build cluster

Mailing list manager with user-friendly web front-end

https://www.list.org/

Utilities, daemons, and filters for processing e-mail

https://mailutils.org/

Dependency generator for makefiles

https://www.x.org/archive/X11R7.5/doc/man/man1/makedepend.1.html

Perl scripts to assist in the generation and application of patches

https://www.vromans.org/johan/software/sw_makepatch.html

Marvell Libertas 88W8335 IEEE 802.11b/g Firmware Kernel Module

http://www.nazgul.ch/malo/

Convert nroff(1) man pages to HTML

https://dickey.his.com/scripts/man2html.html

Convert man pages to HTML

http://man2web.sourceforge.net/

Modern geometric sans-serif font

https://manropefont.com/

CLI for previewing mandoc manual pages with live auto-reload in a pager

https://github.com/0mp/mantra

Old German blackletter handwriting (Suetterlin)

http://www.bryld.dk/hent-filer/

Window manager for the adult in you

https://mate-desktop.org/

Multithreaded SQL database (client)

http://mariadb.org/

Multithreaded SQL database (server)

http://mariadb.org/

Flat design theme for GTK 3, GTK 2, and Gnome-Shell

https://github.com/vinceliuice/Matcha-gtk-theme

Collection of backgrounds for MATE

https://mate-desktop.org/

"meta-port" for the MATE base integrated X11 desktop

https://mate-desktop.org/

Control center for MATE project

https://mate-desktop.org/

Additional UI API for MATE

https://mate-desktop.org/

Collection of icons for the MATE desktop

https://mate-desktop.org/

Implementation of the FreeDesktop Desktop Menu Spec

https://mate-desktop.org/

Send small notifications to your desktop

https://mate-desktop.org/

Panel component for the MATE Desktop

https://mate-desktop.org/

MATE frontend to the PolicyKit framework

https://mate-desktop.org/

Session component for the MATE desktop

https://mate-desktop.org/

MATE settings daemon

https://mate-desktop.org/

Collection of themes and icons for MATE

https://mate-desktop.org/

MATE users guide

Material Design icon set from Google

https://jossef.github.io/material-design-icons-iconfont

Material Design Webfont

https://materialdesignicons.com/

Cross-browser JavaScript display engine for mathematics

https://www.mathjax.org/

Open source Slack-alternative in Golang and React

https://mattermost.org/

Webapp of Mattermost server

https://mattermost.org/

Java project management tool

http://maven.apache.org/

Allows Maven's artifact handling to be used from within an Ant build

http://maven.apache.org/ant-tasks/index.html

Wrapper script for the various installations of Maven

Java project management tool, 3.x branch

http://maven.apache.org/

Java project management tool, 3.3.x branch

http://maven.apache.org/

Implementation of new/posix awk

http://invisible-island.net/mawk

Converts mbox mailboxes to Maildir

http://batleth.sapienti-sat.org/projects/mb2md/

SSL/TLS and cryptography library

https://tls.mbed.org/

Tool for buffering data streams

http://www.maier-komor.de/mbuffer.html

Midnight Commander, a free Norton Commander Clone

http://www.midnight-commander.org/

Lightweight Midnight Commander clone

http://mc.linuxinside.com/

Collects and decodes Machine Check Exception data

http://mcelog.org/