Blocking, shuffling and loss-less compression library

https://blosc.org/

Library for augmenting JDBC drivers with JNDI-bindable DataSources

https://www.mchange.com/projects/c3p0/

Commodore 64 X11 fonts

https://beej.us/c64bdf/

The root certificate bundle from the Mozilla Project

Program to extract Microsoft cabinet (.CAB) files

https://www.cabextract.org.uk/

Fast, cross-platform HTTP/2 web server with automatic HTTPS

https://caddyserver.com

Wayland kiosk

https://www.hjdskes.nl/projects/cage/

Vector graphics library with cross-device output support

https://www.cairographics.org/

C++ interface to cairo

http://cairographics.org

C++ interface to cairo

https://cairographics.org

File manager for the MATE desktop

https://mate-desktop.org/

Lightweight alternative to sudo

https://www.keltia.net/programs/calife

GNUstep application for digital still cameras

http://home.gna.org/gsimageapps/

Framework that allows to access digital cameras

http://home.gna.org/gsimageapps/

Cantarell, a Humanist sans-serif font family

https://wiki.gnome.org/Projects/CantarellFonts

Serialization/RPC system

https://capnproto.org/

Multi-platform, multi-architecture disassembly framework

http://capstone-engine.org/

Audit Cargo.lock for crates with security vulnerabilities

https://rustsec.org/

Cargo C-ABI helpers

https://github.com/lu-zero/cargo-c

Gnome On-Screen keyboard

https://live.gnome.org/Caribou

Managing notes on small cards

Simple tool to analyze noise and distortion of a RF system

https://rfcascade.sourceforge.net/

Monospaced font with programming ligatures

https://github.com/microsoft/cascadia-code

DataStax C/C++ Driver for Apache Cassandra

http://datastax.github.io/cpp-driver/

Highly scalable distributed database

https://cassandra.apache.org/

Highly scalable distributed database

https://cassandra.apache.org/

Header-only test framework for C++

https://github.com/catchorg/Catch2

MS Word/Excel converter to plain ASCII or TeX. TK viewer included

http://www.wagner.pp.ru/~vitus/software/catdoc/

Coin-or Branch and Cut: mixed integer programming solver

https://projects.coin-or.org/Cbc

Reference implementation of the C interface to the legacy Fortran BLAS

http://www.netlib.org/blas/blast-forum/

Tool to minimize the compile time of C/C++ programs

https://ccache.samba.org/

CDDB client bundle GNUstep

http://gsburn.sourceforge.net/

Compare directories and select files to copy

http://home.hccnet.nl/paul.schuurmans/linux/index.html#xdircmp

CDDA extraction tool (also known as ripper)

https://www.xiph.org/paranoia/

Record CD-R[W]s in disk-at-once mode

http://cdrdao.sourceforge.net/

Command-line CD/DVD writing suite

http://www.cdrkit.org/

Tool to lookup CD-ROM dictionaries

https://www.nerimadors.or.jp/~jiro/cdrom2/

CD/DVD/BluRay and ISO-9660 image creation and extraction tools

http://cdrecord.org/

Cellular phone-number read/write tool (in Japan only)

http://www.nurs.or.jp/~kurati/celrw/

Vector graphics tool for GNUstep

http://www.cenon.info/dLinux_gb.html

C++11 library for serialization

https://github.com/USCiLab/cereal

Library for reading and writing files in FITS data format

https://heasarc.gsfc.nasa.gov/docs/software/fitsio/

Cryptographic file system implemented as a user-space NFS server

https://www.bayofrum.net/cgi-bin/fossil/cfs/

Computational geometry library

https://www.cgal.org/

GIF encoder written in C

https://github.com/dloebl/cgif

Fast, lightweight web frontend for Git repositories

https://git.zx2c4.com/cgit/about/

Collection of cut generators for COIN-OR packages that use cuts

https://github.com/coin-or/Cgl

Character art facsimile generator

https://hpjansson.org/chafa/

Embedded scripting language designed for C++

https://chaiscript.com/

Tiling X11 window manager and Vulkan compositor

https://jaelpark.github.io/chamferwm-docs/