SCReenshOT - command line screen capture utility

https://github.com/resurrecting-open-source-projects/scrot

Utility to change screen temperature

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

Interpreter for several adventure games

https://www.scummvm.org/

High-level C++ D-Bus library

https://github.com/Kistler-Group/sdbus-cpp

QML based login manager

https://github.com/sddm/sddm

Cross-platform multimedia development API

https://www.libsdl.org/

SDL-1.2 compatibility layer that uses SDL 2.0 behind the scenes

https://github.com/libsdl-org/sdl12-compat

Cross-platform multimedia development API

https://www.libsdl.org/

SDL graphics drawing primitives and other support functions

http://www.ferzkopp.net/Software/SDL_gfx-2.0/

Simple library to load images of various formats as SDL surfaces

https://www.libsdl.org/projects/SDL_image/

Sample multi-channel audio mixer library

https://www.libsdl.org/projects/SDL_mixer/index.html

Graphically rendering internationalized and tagged text in SDL2

https://github.com/markuskimius/SDL2_Pango

Abstract SDL soundfile decoder

https://icculus.org/SDL_sound/

Library to use TrueType fonts to render text in SDL applications

https://github.com/libsdl-org/SDL_ttf

Audio decoding, resampling and mixing library for SDL

https://github.com/realnc/SDL_audiolib

SDL graphics drawing primitives and other support functions

http://www.ferzkopp.net/Software/SDL_gfx-2.0/

Simple library to load images of various formats as SDL surfaces

https://www.libsdl.org/projects/SDL_image/

Sample multi-channel audio mixer library

https://www.libsdl.org/projects/SDL_mixer/index.html

Small sample cross-platform networking library

http://www.libsdl.org/projects/SDL_net/

SDL_Pango is the SDL API to the Pango text rendering engine of GNOME 2.x

http://sdlpango.sourceforge.net/

SDL audio library and player for some popular sound file formats

http://www.icculus.org/SDL_sound/

Library to use TrueType fonts to render text in SDL applications

https://www.libsdl.org/projects/SDL_ttf/

"Simplified" DocBook XML DTD

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

Open source implementation of a 16bit X86 BIOS

http://www.seabios.org

GNOME application for managing encryption keys (PGP, SSH)

https://wiki.gnome.org/Apps/Seahorse

Minimal seat management daemon and universal library

https://git.sr.ht/~kennylevinsen/seatd

Distributed Object Store and Filesystem

https://github.com/seaweedfs/seaweedfs/wiki

Secure data deletion toolkit

https://www.thc.org/

Filesystem in userspace with transparent encryption and decryption

https://github.com/netheril96/securefs

Checks installed packages for vulnerabilities

http://github.com/laffer1/security-advisory-client/

Scaling, colorspace conversion, and dithering library

https://github.com/sekrit-twc/zimg

Reliable, highly configurable mail transfer agent with utilities

https://www.sendmail.org/

Perl-script to send xmpp (jabber) messages

https://sendxmpp.hostname.sk/

C library for RDF syntax

https://drobilla.net/software/serd

Serf HTTP client library

https://serf.apache.org/

Manage utmp/wtmp entries for non-init X clients

Set the keyboard using the X Keyboard Extension

https://www.freedesktop.org/Software/xorg

Wrapper library around CGAL for PostGIS

https://oslandia.gitlab.io/SFCGAL/

Set of utilities that send SCSI commands to devices

http://sg.danny.cz/sg/sg3_utils.html

Fonts from the SGI ProPack 1.4 (originally for Linux)

http://oss.sgi.com/projects/sgi_propack/

Generates groff and HTML from linuxdoc and docbook SGML documents

SGML parser

GLSL/HLSL to SPIR-V shader compiler

https://github.com/google/shaderc

Interoperability between desktops and collaborative environments

http://oscaf.sourceforge.net

MIME types database from the freedesktop.org project

https://www.freedesktop.org/wiki/Software/shared-mime-info/

Collection of shareware ATM fonts from the CICA archives

Pack, send, and unpack shell archives; synchronize via e-mail

http://www.gnu.org/s/sharutils/

Generic script compiler

http://www.datsi.fi.upm.es/~frosal/frosal.html

Benchmark utility for POSIX shell comparison

https://github.com/shellspec/shellbench

Font dumper for the X font server

https://www.x.org/