Free software programmed in C

cURL (pronounced like "curl", ) is a free and open source CLI app for uploading and downloading individual files. It can download a URL from a web server over HTTP, and supports a variety of other network protocols, URI schemes, multiple versions of HTTP, and proxying. The project consists of a library (libcurl) and command-line tool (curl), which have been widely ported to different computing platforms. It was created by Daniel Stenberg, who is still the lead developer of the project.

personal information manager software and workgroup information management tool for GNOME

Evince (), also known as GNOME Document Viewer, is a free and open-source document viewer supporting many document file formats including PDF, PostScript, DjVu, TIFF, XPS and DVI. It is designed for the GNOME desktop environment.

Gnumeric is a spreadsheet program that is part of the GNOME Free Software Desktop Project. Gnumeric version 1.0 was released on 31 December 2001. Gnumeric is distributed as free software under the GNU General Public License; it is intended to replace proprietary spreadsheet programs like Microsoft Excel. Gnumeric was created and developed by Miguel de Icaza, but he has since moved on to other projects. The maintainer was Jody Goldberg.

thumb|Preferred badge for promoting apps on Flathub since 2023, English version Flatpak is a utility for software deployment and package management for Linux. It provides a sandbox environment in which users can run application software in (partial) isolation from the rest of the system. Flatpak was known as xdg-app until 2016.

thumb|Customized Geany IDE

ClamAV (Clam AntiVirus) is a free software, cross-platform antimalware toolkit able to detect many types of malware, including viruses. It was developed for Unix and has third party versions available for AIX, BSD, HP-UX, Linux, macOS, OpenVMS, OSF (Tru64), Solaris and Haiku. As of version 0.97.5, ClamAV builds and runs on Microsoft Windows. Both ClamAV and its updates are made available free of charge. One of its main uses is on mail servers as a server-side email virus scanner.

Linux kernel security module

Dillo is a minimalistic web browser particularly intended for older or slower computers and embedded systems. It supports only plain HTML/XHTML (with CSS rendering) and images over HTTP and HTTPS; scripting is ignored entirely. Current versions of Dillo can run on Linux, BSD, macOS, IRIX and Cygwin. Due to its small size, it is a popular choice for lightweight Linux distributions. Dillo is free software, released under the GNU GPL-3.0-or-later.

X Multimedia System (XMMS) is an audio player for Unix-like systems released under a free software license.

mail transfer agent

free web browser based on Floorp

FFmpeg is a free and open-source software project consisting of a suite of libraries and programs for handling video, audio, and other multimedia files and streams. At its core is the command-line ffmpeg tool itself, designed for processing video and audio files. It is widely used for format transcoding, basic editing (trimming and concatenation), video scaling, video post-production effects, and standards compliance (SMPTE, ITU).

GNU version of the Emacs text editor

Redis (; Remote Dictionary Server) is an in-memory key–value database, used as a distributed cache and message broker, with optional durability. Because it holds all data in memory and because of its design, Redis offers low-latency reads and writes, making it particularly suitable for use cases that require a cache.

BusyBox is an implementation of many Unix commands in a single executable file. It runs in many POSIX environments including Linux, Android, and FreeBSD, although many of the tools it provides are designed to work with interfaces provided by the Linux kernel. It was specifically created for embedded operating systems with very limited resources. The authors dubbed it "The Swiss Army knife of Embedded Linux", as the single executable replaces basic functions of more than 300 common commands. It is released as free software under the terms of the GNU General Public License v2, after controversia

GnuCash is an accounting program that implements a double-entry bookkeeping system. It was initially aimed at developing capabilities similar to Intuit, Inc.'s Quicken application, but also has features for small business accounting. Recent development has been focused on adapting to modern desktop support-library requirements.

Irssi ( ) is an Internet Relay Chat (IRC) client program for Linux, FreeBSD, macOS and Microsoft Windows. It was originally written by Timo Sirainen, and released under the terms of the GNU GPL-2.0-or-later in January 1999.

package of GNU software containing reimplementations for many of the basic tools, such as cat, ls, and rm, used on Unix-like operating

iptables is a user-space utility program that allows a system administrator to configure the IP packet filter rules of the Linux kernel firewall, implemented as different Netfilter modules. The filters are organized in a set of tables, which contain chains of rules for how to treat network traffic packets. Different kernel modules and programs are currently used for different protocols; iptables applies to IPv4, ip6tables to IPv6, arptables to ARP, and '''' to Ethernet frames.

CUPS (formerly an acronym for Common UNIX Printing System) is a modular printing system for Unix-like computer operating systems which allows a computer to act as a print server. A computer running CUPS is a host that can accept print jobs from client computers, process them, and send them to the appropriate printer.

Compiz () is a compositing window manager for the X Window System, using 3D graphics hardware to create fast compositing desktop effects for window management. Effects, such as a minimization animation or a cube workspace, are implemented as loadable plugins. Because it conforms to the ICCCM conventions, Compiz can be used as a substitute for the default Mutter or Metacity, when using GNOME Panel, or KWin in KDE Plasma Workspaces. Internally Compiz uses the OpenGL library as the interface to the graphics hardware.

audio player, free and open source software

free and open-source geospatial processing engine

graphics software

PDF reader, free software

MiKTeX is a free and open-source distribution of the TeX/LaTeX typesetting system compatible with Linux, MacOS, and Windows. It also contains a set of related programs. MiKTeX provides the tools necessary to prepare documents using the TeX/LaTeX markup language, as well as a simple TeX editor, TeXworks. The name comes from the login credentials of the chief developer Christian Schenk, MiK for Micro-Kid.

diagramming software

GNOME application for burning CDs and DVDs

According to the Free Software Foundation Latin America, Linux-libre is a modified version of the Linux kernel that contains no binary blobs, obfuscated code, or code released under proprietary licenses. In the Linux kernel, those types of code are mostly used for proprietary firmware images. While generally redistributable, they do not give the user the freedom to audit, modify, or, consequently, redistribute their modified versions. The GNU Project keeps Linux-libre in synchronization with the mainline Linux kernel.

netcat (often abbreviated to nc) is a computer networking utility for reading from and writing to network connections using TCP or UDP. The command is designed to be a dependable back-end that can be used directly or easily driven by other programs and scripts. At the same time, it is a feature-rich network debugging and investigation tool, since it can produce almost any kind of connection its user could need and has a number of built-in capabilities.

BitTorrent client

virtualization module in the Linux kernel

authoritative programming book by Brian Kernighan and Dennis Ritchie, the developers of the C programming language

rsync (remote sync) is a utility for transferring and synchronizing files between a computer and a storage drive and across networked computers by comparing the modification times and sizes of files. It is commonly found on Unix-like operating systems and is under the GPL-3.0-or-later license.

ImageMagick, invoked from the command line as magick, is a free and open-source cross-platform software suite for displaying, creating, converting, modifying, and editing raster images. It can read and write over 200 image file formats and is widely used in open-source applications. ImageMagick was created by John Cristy in 1987.

open source instant messaging and VoIP client

FontForge is a FOSS font editor which supports many common font formats. Developed primarily by George Williams until 2012, FontForge is free software and is distributed under a mix of the GNU General Public License Version 3 and the 3-clause BSD license. It is available for operating systems including Linux, Windows, and macOS, and progress has been made on localizing it into 21 languages including Spanish, Chinese, Russian, Swedish, Korean, and Croatian.

text and HTML editor

lighttpd (prescribed pronunciation: "lighty") is an open-source web server optimized for speed-critical environments. It was originally written by Jan Kneschke as a proof-of-concept of the c10k problem – how to handle 10,000 connections in parallel on one server, but has gained worldwide popularity. Its name is a portmanteau of "light" and "httpd".

GStreamer is a pipeline-based multimedia framework that links together a wide variety of media processing systems to complete complex workflows. For instance, GStreamer can be used to build a system that reads files in one format, processes them, and exports them in another. The formats and processes can be changed in a plug and play fashion.

Pango (stylized as Παν語) is a text (i.e. glyph) layout engine library which works with the HarfBuzz shaping engine for displaying multi-language text.

CPython is the reference implementation of the Python programming language. Written in C and Python, CPython is the default and most widely used implementation of the Python language.

file manager application

Galeon is a discontinued Gecko-based web browser that was created by Marco Pesenti Gritti with the goal of delivering a consistent browsing experience to GNOME desktop environment. It gained some popularity in the early 2000s due to its speed, flexibility in configuration and features.

web browser and web editor

Metacity (pronounced ) was the default window manager used by the GNOME 2 desktop environment until it was replaced by Mutter in GNOME 3. It is still used by GNOME Flashback, a session for GNOME 3 that provides a similar user experience to the Gnome 2.x series sessions.

Media player software of the desktop environment GNOME

ncurses (new curses) is a programming library for creating textual user interfaces (TUIs) that work across a wide variety of terminals. It is written in a way that attempts to optimize the commands that are sent to the terminal, to reduce the latency experienced when updating the displayed content.

CMake is a free, cross-platform, software development tool for building applications via compiler-independent instructions. It also can automate testing, packaging and installation. It runs on a variety of platforms and supports many programming languages.

thumb|dwm's xinerama support: tiling on two screens simultaneously

zlib ( or "zeta-lib", ) is a data format and a lossless data compression software library created by Jean-loup Gailly and Mark Adler. The library implements the Deflate algorithm and supports compressing and decompressing data using the zlib data format, the gzip file format, or simply as a Deflate stream.

archive manager of the GNOME desktop environment (former File Roller)

graphics-related software library

tcpdump is a data-network packet analyzer computer program that runs under a command line interface. It allows the user to display TCP/IP and other packets being transmitted or received over a network to which the computer is attached. Distributed under the BSD license, tcpdump is free software.

gretl is computer software, an open-source statistical package, mainly for econometrics. The name is an acronym for Gnu Regression, Econometrics and Time-series Library.

xterm is the standard terminal emulator for the X Window System. It allows users to run programs which require a command-line interface.

simple and lightweight window manager with few dependencies

Darktable (stylized as darktable) is a free and open-source photography application and raw developer. Rather than being a raster graphics editor like Adobe Photoshop or GIMP, it comprises a subset of image editing operations specifically aimed at non-destructive raw image post-production. It is primarily focused on improving a photographer's workflow by facilitating the handling of large numbers of images. It is freely available in versions tailored for most major Linux distributions, macOS, Solaris and Windows and is released under the GPL-3.0-or-later software license.

tcsh ( “tee-see-shell”, “tee-shell”, or as “tee see ess aitch”, tcsh) is a Unix shell based on and backward compatible with the C shell (csh).