SpiderOak Client (Linux version)

https://spideroak.com/

Bi-directional translation between SPIR-V and LLVM IR

https://github.com/KhronosGroup/SPIRV-LLVM-Translator

Tools for processing SPIR-V intermediate shader language modules

https://github.com/KhronosGroup/SPIRV-Tools

Monospaced bitmap fonts for Xorg and vt(4)

https://github.com/fcambus/spleen

Tool for statically checking sourcecode for security vulnerabilities

http://www.splint.org/

Lightweight Spotify client using Qt

https://github.com/kraxarn/spotify-qt

Spotify for the terminal written in Rust

https://github.com/Rigellute/spotify-tui

Spotify daemon

https://github.com/Spotifyd/spotifyd

The Spring Framework for Java

https://www.springframework.org/

Double entry accounting system

http://www.sql-ledger.org/

Lightweight database abstraction layer

SQLite backed FUSE file system

https://www.nongnu.org/libsqlfs/

SQL database engine in a C library

http://www.sqlite.org/

SQL database engine in a C library

https://www.sqlite3.org/

Set of tools to manipulate squashfs images

https://squashfs.sourceforge.net/

New set of tools and libraries to work with SquashFS images

https://infraroot.at/projects/squashfs-tools-ng/

Mount a squashfs archive and treat it like a local file system

https://github.com/vasi/squashfuse

HTTP Caching Proxy

http://www.squid-cache.org/

Webmail system which accesses mail over IMAP

http://www.squirrelmail.org/

Library for serialising LV2 atoms to/from RDF

http://drobilla.net/software/sratom

Secure Reliable Transport (SRT) Protocol

https://www.srtalliance.org/

Chat over SSH

https://github.com/shazow/ssh-chat

Mount remote directories over ssh

https://github.com/libfuse/sshfs

Protect hosts from brute-force attacks against SSH and other services

https://www.sshguard.net/

State Threads Library for Internet Applications

http://state-threads.sourceforge.net/

Library that supports startup notification spec from freedesktop.org

https://www.freedesktop.org/wiki/Software/startup-notification/

Monospace font created for the French magazine Etapes

https://raphaelbastide.com/steps-mono

OpenType Unicode fonts for Scientific, Technical, and Math texts

http://www.stixfonts.org/

Synthesis ToolKit in C++

https://ccrma.stanford.edu/software/stk

Command-line utility that pipes video streams

https://streamlink.github.io/

Stuffit Archive Creator and Expander

http://my.smithmicro.com/unix/stuffit/

Advanced IP/IPv6 subnet calculation and discovery

http://www.seccuris.com

Subsonic streaming media server, standalone version

http://www.subsonic.org

Version control system

http://subversion.apache.org/

Version control system, long-time-support version

http://subversion.apache.org/

Receives/sends news to/from localhost via NNTP

https://github.com/lazarus-pkgs/suck

Allow others to run commands as root

https://www.sudo.ws/

Font for programmers and command line users

https://www.kutilek.de/sudo-font

C library for loading and wrapping LV2 plugin UIs

http://drobilla.net/software/suil/

SuiteSparse is a set of packages for sparse matrices calculation

http://faculty.cse.tamu.edu/davis/suitesparse.html

Symmetric approximate minimum degree

https://faculty.cse.tamu.edu/davis/suitesparse.html

Permutation to block triangular form

https://faculty.cse.tamu.edu/davis/suitesparse.html

Symmetric approximate minimum degree

https://faculty.cse.tamu.edu/davis/suitesparse.html

Constrained column approximate minimum degree ordering

https://faculty.cse.tamu.edu/davis/suitesparse.html

Sparse CHOLesky MODification package

https://faculty.cse.tamu.edu/davis/suitesparse.html

Column approximate minimum degree ordering algorithm

https://faculty.cse.tamu.edu/davis/suitesparse.html

Common library for SuiteSparse

https://faculty.cse.tamu.edu/davis/suitesparse.html

Concise Sparse Matrix package

https://faculty.cse.tamu.edu/davis/suitesparse.html

Extended version of CSparse

https://faculty.cse.tamu.edu/davis/suitesparse.html

Graph algorithms in the language of linear algebra

https://faculty.cse.tamu.edu/davis/suitesparse.html