Free software programmed in C

Erwise is an early discontinued web browser, and the first that was available for the X Window System.

EasyTag (stylised as EasyTAG) is a free and open-source graphical tag editor that is part of the GNOME project. EasyTag runs on Linux and Microsoft Windows, and there was an attempt to bring EasyTAG to OS X circa 2014. It is written in C and relies on GTK+ and id3lib for graphics and ID3 tag handling respectively. As of version 2.1.1, EasyTag also uses the tag manipulation library provided by the MAD project, for support of ID3v2.4.

Potrace () is cross-platform, open-source software which converts bitmapped images into vector graphics. It is written and maintained by Peter Selinger.

xrdp is a free and open-source implementation of Microsoft RDP (Remote Desktop Protocol) server that enables operating systems other than Microsoft Windows (such as Linux and BSD-style operating systems) to provide a fully functional RDP-compatible remote desktop experience. It works by bridging graphics from the X Window System to the client and relaying controls from the client back to X Window Server.

GPSBabel is a cross-platform, free software to transfer routes, tracks, and waypoint data to and from consumer GPS units, and to convert between GPS data formats. It has a command-line interface and a graphical interface for Windows, macOS, and Linux users.

right|thumb|Hildon in Ubuntu Mobile and Embedded Edition

stacking window manager for the X Window System on OpenBSD

REDIRECT Tiling window manager#wmii

thumb|Slaptget print screen|250px|right

TinySPARQL (formerly known as Tracker) is a file indexing and search framework for Linux and other Unix-like systems. It is written in the C programming language.

software package intended for solving large-scale linear programming (LP), mixed integer programming (MIP), and other related problems.

DNS server

alternative SSH-server and client

Skencil, formerly called Sketch, is a free software vector graphics editor, released under the GNU Lesser General Public License.

LinuxCNC (formerly Enhanced Machine Controller or EMC2) is a free, open-source Linux software system that implements computer numerical control (CNC) capability using general purpose computers to control CNC machines. It's mainly intended to run on PC AMD x86-64 systems. Designed by various volunteer developers at linuxcnc.org, it is typically bundled as an ISO file with a modified version of Debian Linux which provides the required real-time kernel.

OpenAFS is an open-source implementation of the Andrew distributed file system (AFS). AFS was originally developed at Carnegie Mellon University, and developed as a commercial product by the Transarc Corporation, which was subsequently acquired by IBM. At LinuxWorld on 15 August 2000, IBM announced their plans to release a version of their commercial AFS product under the IBM Public License. This became OpenAFS. Today, OpenAFS is actively developed for a wide range of operating system families including: AIX, Mac OS X, Darwin, HP-UX, Irix, Solaris, Linux, Microsoft Windows, FreeBSD, NetBSD.

TIC-80 is a free and open-source fantasy video game console for making, playing, and sharing games on a limited platform that mimics the 8-bit systems of the 1980s. It has built-in code, sprite, map, music, and sound effect editors, as well as a command line interface that allow users to develop and edit games within the fantasy console.

'''''Rocks'n'Diamonds''' is an open source puzzle video game created by Holger Schemel and published in 1995 by Artsoft Entertainment. It is a clone of Boulder Dash, Supaplex, Emerald Mine, and Sokoban''.

Newlib is a C standard library implementation intended for use on embedded systems. It is a conglomeration of several library parts, all under free software licenses that make them easily usable on embedded products.

mpg123 is a free and open-source audio player. It supports MPEG audio formats, including MP3.

web browser and web authoring tool for Unix

UltraDefrag is a disk defragmentation utility for Microsoft Windows. Prior to version 8.0.0 it was released under the GNU General Public License.

Seafile is an open-source, cross-platform file-hosting software system. Files are stored on a central server and can be synchronized with personal computers and mobile devices through apps. Files on the Seafile server can also be accessed directly via the server's web interface. Seafile's functionality is similar to other popular file hosting services such as Dropbox and Google Drive. The primary difference between Seafile and Dropbox/Google Drive is that Seafile is a self-hosted file sharing solution for private cloud applications. In private clouds, storage space and client connection limits

PCSX is a free and open-source, video game console emulator that allows software designed to be used with the Sony PlayStation to run on personal computers. Over the years, development changed hands several times with PCSX-Reloaded (PCSXR) now being the main version. As of 2021, the emulator seems to be no longer under active development. A newer, actively maintained fork of PCSX-Reloaded is PCSX-Redux.

GNOME disk utility

ncdu (NCurses Disk Usage) is a disk utility for Unix systems. Its name refers to its similar purpose to the du utility, but ncdu uses a text-based user interface under the [n]curses programming library. Users can navigate the list using the arrow keys and delete files that are taking up too much space by pressing the 'd' key. It provides a swift and efficient way to view directories that are taking up disk space, and was primarily meant for remote shells. It runs on UNIX-based systems, such as Linux, BSD, and POSIX. Users can install ncdu by running a package manager command in their terminal

application that adjusts the computer display's color temperature

open source high availability resource manager software

PARI/GP is a computer algebra system with the main aim of facilitating number theory computations. Versions 2.1.0 and higher are distributed under the GNU General Public License. It runs on most common operating systems.

FluidSynth, formerly named iiwusynth, is a free open source software synthesizer which converts MIDI note data into an audio signal using SoundFont technology without need for a SoundFont-compatible soundcard. FluidSynth can act as a virtual MIDI device, able to receive MIDI data from any program and transform it into audio on-the-fly. It can also read in SMF (.mid) files directly. On the output side, it can send audio data directly to an audio device for playback, or to a Raw or Wave file. It can also convert a SMF file directly to an audio file in faster-than-real-time. The combination of th

open-source, cross-platform illustration program

Sound eXchange (SoX) is a cross-platform audio editing software. It has a command-line interface, and is written in standard C. It is free software, licensed under GPL-2.0-or-later, with libsox licensed under LGPL-2.1-or-later, and distributed by Chris Bagwell through SourceForge.

user interface dock for Linux

news reader software

GOCR (or JOCR) is a free optical character recognition program, initially written by Jörg Schulenburg. It can be used to convert or scan image files (portable pixmap or PCX) into text files.

Seed7 is an extensible general-purpose programming language designed by Thomas Mertes. It is syntactically similar to Pascal and Ada. Along with many other features, it provides an extension mechanism. Seed7 supports introducing new syntax elements and their semantics into the language, and allows new language constructs to be defined and written in Seed7. For example, programmers can introduce syntax and semantics of new statements and user defined operator symbols. The implementation of Seed7 differs significantly from that of languages with hard-coded syntax and semantics.

CD ripping program

thttpd (tiny/turbo/throttling HTTP server) is an open source software web server from ACME Laboratories, designed for simplicity, a small execution footprint and speed.

C library for arbitrary-precision floating-point arithmetic

Pure-FTPd is a free (ISC license) FTP Server with a strong focus on software security. It can be compiled and run on a variety of Unix-like computer operating systems including Linux, OpenBSD, NetBSD, FreeBSD, DragonFly BSD, Solaris, Tru64, Darwin, Irix and HP-UX. It has also been ported to Android.

zswap is a Linux kernel feature that provides a compressed write-back cache for swapped pages, as a form of virtual memory compression. Instead of moving memory pages to a swap device when they are to be swapped out, zswap performs their compression and then stores them into a memory pool dynamically allocated in the system RAM. Later writeback to the actual swap device is deferred or even completely avoided, resulting in a significantly reduced I/O for Linux systems that require swapping; the tradeoff is the need for additional CPU cycles to perform the compression.

programming language, primarily used to create database/business programs

ARToolKit is an open-source computer tracking library for creation of augmented reality applications that overlay virtual imagery on the real world. Currently, it is maintained as an open-source project hosted on GitHub.

interpreter for the Ruby programming language

Linux kernel's built-in crash dump mechanism

process scheduler in Linux

group communication system

CircuitPython is an open-source derivative of the MicroPython programming language targeted toward students and beginners. Development of CircuitPython is supported by Adafruit Industries. It is a software implementation of the programming language, written in C. It has been ported to run on several modern microcontrollers.

Ext2Fsd (short for Ext2 File System Driver) is a free Installable File System driver written in C for the Microsoft Windows operating system family. It facilitates read and write access to the ext2, ext3 and ext4 file systems.

TigerVNC is an open source Virtual Network Computing (VNC) server and client software, started as a fork of TightVNC in 2009. The client supports Windows, Linux and macOS. The server supports Linux. There is no server for macOS and as of release 1.11.0 the Windows server is no longer maintained.

SeaBIOS is an open-source implementation of an x86 BIOS, serving as a freely available firmware for x86 systems. Aiming for compatibility, it supports standard BIOS features and calling interfaces that are implemented by a typical proprietary x86 BIOS. SeaBIOS can either run on bare hardware as a coreboot payload, or can be used directly in emulators such as QEMU and Bochs.

GGPO (Good Game Peace Out) is middleware designed to help create a near-lagless online experience for various emulated arcade games and fighting games. The program was created by Tony Cannon, co-founder of fighting game community site Shoryuken and the popular Evolution Championship Series.

project aimed at preserving browser games and Flash animations

free software

GraphicsMagick is a fork of ImageMagick, emphasizing stability of both programming API and command-line options. It was branched off ImageMagick's version 5.5.2 in 2002 after irreconcilable differences emerged in the developers' group.

Rawstudio is a free and open source stand-alone application software to read and manipulate images in raw image formats from digital cameras. It is designed for working rapidly with a large volume of images, whereas similar tools are designed to work with one image at a time.

GrafX2 is a bitmap graphics editor inspired by the Amiga programs Deluxe Paint and Brilliance. It is free software and distributed under the GPL-2.0-only license.

Netpbm (formerly Pbmplus) is an open-source package of graphics programs and a programming library. It is used primarily in Unix, where it is found in all major open-source operating system distributions, but also works on Microsoft Windows, macOS, and other operating systems.

systemd-boot is a free and open-source boot manager, previously known as gummiboot.

TupiTube (previously KTooN and Tupi 2D) is a free and open-source 2D animation software developed and maintained by the Colombian startup, Mae Floresta. It is available for Windows, Mac OS X, Linux and Android under the terms of the GNU GPL-2.0 or later license.