firecrypt/awesome-c

Continuing the development of awesome-c list on GitHub

awesome-c

A curated list of C good stuff. This list contains only free software for code, and sellers who aren't evil for physical resources.

LOOKING FOR MAINTAINERS: This list is currently pretty much inactive. I'm looking for maintainers that can make it great again. See #26 for more info, but the process is simple: add or fix a couple of things in this list and you'll become a contributor to a 700+ stars list.

This list was previously maintained by @kozross. He decided to switch the list to a new platform, so I've decided to fork it so we could keep it on GitHub.

Contents

Contents

• Build Systems
• Compilers
• Compression
• Crypto
• Database
• Deep Learning
• Documentation Generation
• Editors
• Embedded Systems
  • RTOS
• Environments
• Frameworks
• Game Programming
  • Engines
  • Resources
• Generic Programming
• Graphics
• Graphical User Interface
• Image Processing
• JSON
• Learning, Reference and Tutorials
  • Online
    • Reference
    • Beginner
    • Intermediate
    • Advanced
    • Self-study courses
  • Physical
    • Reference
    • Beginner
    • Intermediate
    • Advanced
• Multimedia
• Networking and Internet
  • Web Frameworks
• Numerical
• Parallel Programming
• Regex
• Serialization
• Source Code Collections
• Standard Libraries
• String Manipulation
• Testing
• Text Editor Extensions
  • Emacs
  • Vim
• Tools
• Utilities
• XML

Build Systems

These are tools to automate the building and testing of projects in C.

• aimake - Build tool designed to avoid complex configurations. [GNU GPL3 or later]
• Autoconf - Extensible package of M4 macros that produce shell scripts to automatically configure software source code packages. Part of the Autotools. [GNU GPL3 or later]
• Automake - Tool for automatically generating Makefile.in files compliant with the GNU Coding Standards. Requires the use of Autoconf. Part of the Autotools. [GNU GPL3 or later]
• CMake - Tools for cross-platform building, testing, and packaging. [3-clause BSD]
• Jam - Build system, designed to be easier than make. Understands C build rules implicitly. [Jam License]
• Libtool - Generic library support script. Part of the Autotools. [GNU GPL3 or later]
• Meson - Extremely fast, user-friendly build system. Based on Ninja. [Apache2.0]
• Premake - Build script generator for toolsets like Visual Studio, Xcode, or GNU Make. [3-clause BSD]

Compilers

• Clang - C compiler for LLVM. Supports C11. [NCSA]
• CompCert - Fully-verified C compiler. Supports almost all of C89. [GNU GPL2.1 or later]
• GCC - Provides a C compiler as part of its compiler set. Supports C11 and OpenMP. [GNU GPL3 or later]
• PCC - Venerable C compiler. Supports C99. [Various free licenses]
• TCC - Tiny C Compiler; a small, fast C compiler. Supports C99 (except complex types). [GNU LGPL2.1 only]

Compression

• libzip - A C library for reading, creating, and modifying zip archives. [3-clause BSD]
• lzo - Very fast data compression library. [GNU GPL2.1]
• zlib - Massively-spiffy yet delicately-unobtrusive compression library. [3-clause BSD]

Crypto

• GnuTLS - Secure communication library, implementing SSL, TLS and DTLS. [GNU LGPL2.1 or later]
• libgcrypt - General-purpose cryptography library, with a range of available ciphers. [GNU LGPL2.1 or later (code)] and [GNU GPL2.1 or later (manual and tools)]
• OpenSSL - Implementation of the SSL and TLS protocols, and also includes a cryptography library. [Dual Licensed under the OpenSSL License and the SSLeay License]
• libsodium - Modern and easy-to-use crypto library. [Expat]
• libtomcrypt - Fairly comprehensive, modular and portable cryptographic toolkit. [Public domain]
• mbed TLS - Another crypto implementation for C. [Apache2.0]

Database

This lists databases and data stores with C APIs.

• BerkeleyDB - Library for a high-performance embedded database for key-value data. [GNU AGPLv3 only]
• Hiredis - Minimalistic client library for Redis. [3-clause BSD]
• LMDB - Ultra-fast, ultra-compact key-value embedded data store. [newOpenLDAP]
• MariaDB - Robust, scalable and reliable SQL server, designed to be a drop-in replacement for MySQL. [3-clause BSD]
• mongo-c-driver - High-performance client library for MongoDB. [Apache2.0]
• PostgreSQL - Powerful object-relational database system. [PostgreSQL licence]
• recutils - Set of tools and a C library for accessing human-editable, plaintext database files called recfiles. [GNU GPL3 or later]
• Redis - Advanced key-value store. [3-clause BSD]
• sophia - Modern, embeddable key-value database. [FreeBSD]
• SQLite - Self-contained, serverless, zero-configuration, transactional SQL database engine with a C interface. [Public domain]
• UnQLite - Self-contained, serverless, zero-configuration, transactional NoSQL engine with a C interface. [FreeBSD]

Deep Learning

• Darknet - Open source neural network framework written in C and CUDA. It is fast, easy to install, and supports CPU and GPU computation.

Documentation Generation

• Cxref - Generates documentation of C programs in either LaTeX, HTML, RTF or SGML. [GNU GPL2.1 only]
• DocOnce - Modestly-tagged markup language that can be used to generate a range of formats. [3-clause BSD]
• Doxygen - The de-facto standard tool for generating C documentation from annotated sources. Can generate a large range of formats. [GNU GPL2.1 only]
• GTK-Doc - Tool for generating C documentation from annotated sources. Has support for the Autotools. [GNU GPL2.1 only (code)] or [GNU FDL1.1]

Editors

These are specifically fancier, IDE-type editors. If you want a programmer's text editor, look elsewhere. Besides, whatever choice you make most likely supports C anyway.

• Anjuta DevStudio - The GNOME IDE. [GNU GPL2.1 only]
• Atom - Hackable text editor for the 21st century. [MIT]
• Code::Blocks - Extensible, configurable IDE supporting C. [GNU GPL3 only]
• CodeLite - Cross-platform IDE. [GNU GPL2.1 only]
• Eclipse - IDE written in Java. [EPL]
• Geany - Very small and fast IDE. [GNU GPL2.1 or later]
• KDevelop - The KDE IDE. [GNU GPL2.1 only]
• Qt Creator - Cross-platform IDE written with C++ and Qt, part of the Qt SDK. Supports Clang Code Model. [GNU GPL3 with Qt exception only]

Embedded Systems

These are projects that allow one to work with microcontrollers and other resource constrained architectures.

RTOS

A real-time operating system (RTOS) is intended to serve real-time applications that process data with low latency delay.

• Amazon FreeRTOS - RTOS for microcontrollers that makes small, low-power edge devices easy to program. [MIT]
• ChibiOS - RTOS with complete development environment (HAL, drivers, support files, and tools). [Various]
• Contiki - Connect low-cost, low power microcontrollers to the Internet. [3-clause BSD]
• Zephyr Project - Scalable real-time RTOS supporting multiple hardware architectures, optimized for resource constrained devices. [Apache2.0]

Environments

This is a list of technologies designed to bring Windows into the 21st century with respect to support for C.

• Cygwin - Designed to emulate a POSIX-compatible environment extensively under Windows. [Various free licenses]
• MinGW-w64 - Minimalist environment for C development on Windows with 64 bit support. [Various free licenses]

Frameworks

This section has big libraries that provide data structures and other stuff you expect of a 'modern' standard library.

• APR - Apache Portable Runtime; another library of cross-platform utility functions. [Apache2.0]
• C Algorithms - Collection of common algorithms and data structures for C. [ISC]
• CPL - The Common Pipeline Library; a set of libraries designed to be a comprehensive, efficient and robust software toolkit. [GNU GPL2.1 only]
• EFL - Large collection of useful data structures and functions. [Various free licenses]
• GLib - Library of utility functions and structures, designed to be portable, efficient and powerful. [GNU LGPL2.1 only]
• GIO - Modern and easy-to-use VFS API. [GNU LGPL2.1 only]
• GObject - Object-oriented system and object model for C. [GNU LGPL2.1 only]
• libnih - Lightweight library of C functions and structures. [GNU GPL2.1 only]
• libU - Small library of basic utilities, including memory allocation, string manipulation and logging. [3-clause BSD]
• PBL - Large library of utilities, featuring data structures, among other things. [GNU LGPL2.1 or later (library)] or [GNU GPL2.1 or later (test code)]
• qlibc - Simple and powerful C library, designed as a replacement for GLib while focusing on being small and light. [qLib license (similar to FreeBSD)]
• stb - Range of single-file libraries for C. [Public domain]

Game Programming

Engines

These are provided as examples of C game programming code.

• Corange - Game engine in pure C. [FreeBSD]
• Darkplaces - Modified version of the Quake2 engine. [GNU GPL2.1 only]
• ioquake3 - The Quake3 engine, freed at last. [GNU GPL2.1 only]
• Orx - Portable, lightweight, plugin-based, data-driven, 2D-oriented game engine. [zlib]
• Quake - The Quake engine. [GNU GPL2.1 only]
• Quake2 - The Quake2 engine. [GNU GPL2.1 only]
• Spearmint - Engine designed for FPS games. [GNU GPL3 or later]

Resources

These are libraries of all sorts that are useful for game programming.

• Allegro - Cross-platform, video game development and multimedia library. [zlib]
• Chipmunk2D - Fast and lightweight 2D game physics library. [Expat]
• CSFML - Binding for SFML in C. [zlib]
• FreeGLUT - Alternative to the OpenGL Utility Toolkit. Allows the creation and management of windows with OpenGL contexts. [X11]
• GLFW - Multi-platform library for creating windows with OpenGL contexts. [zlib]
• libao - Cross-platform audio library with a wide variety of outputs. [GNU GPL2.1 or later]
• RetroArch - The reference frontend for libretro. [GNU GPL3 only]
• SDL - Cross-platform library designed to provide low-level access to audio, keyboard, mouse, joystick and graphics hardware via OpenGL. [zlib]
• SDL2- Cross-platform development library designed to provide low level access to audio, keyboard, mouse, joystick, and graphics hardware via OpenGL. This is the most current version. [zlib]
• raylib - Simple and easy-to-use library to learn videogames programming. zlib

Generic Programming

• klib - Small and lightweight implementations of common algorithms and data structures. [Expat]

Graphics

• Cairo -2D graphics library. [GNU LGPL2.1 only] or [MPLv1.1]
• Cogl - GPU graphics and utilities API. [Expat]
• Clutter - UI library based on OpenGL. [GNU LGPL2.1 only]
• heman - Tiny library of image utilities dealing with height maps, normal maps, distance fields and the like. [Expat]
• libcaca - ASCII renderer for terminal-based interfaces. [WTFPLv2]
• libimagequant - Small, portable library for high-quality conversion of RGBA images to 8-bit indexed colour images. [FreeBSD]
• libjpeg-turbo - Faster library for reading and writing JPEG files. [Various free licenses]
• libpng - The official PNG reference library. [libpng license]
• libxmi - Function library for rasterizing 2D vector graphics. [GNU GPL3 or later]
• mozjpeg - Improved JPEG encoder. [3-clause BSD]
• OpenGL - The industry standard for high-performance graphics, with a native C binding. [Various free licenses]

Graphical User Interface

These are specifically widget toolkits.

• GTK+ - Cross-platform widget toolkit. [GNU LGPL2.1 only]
• IUP - Another cross-platform widget toolkit. [Expat]
• Tk - Basic widget toolkit. Part of Tcl/Tk. [Tcl/Tk License]
• XForms Toolkit - Widget toolkit designed for the XWindow system. [GNU LGPL2.1 only]
• nuklear - Single-header ANSI C gui library. [Public domain]

Image Processing

• libccv - Modern Computer Vision Library. [3-clause BSD]

JSON

• Jansson - C library for encoding, decoding and manipulating JSON. [Expat]
• jsmn - Minimalistic JSON parser. [Expat]
• json-c - Library for working with JSON. [Expat]
• WJElement - Advanced JSON manipulation library, with support for JSON Schema. [LGPL, any version]
• YAJL - Fast C JSON streaming parser library. [ISC]

Learning, Reference and Tutorials

This is a list of resources for learning C programming in general, or something useful relating to C programming.

Online

Reference

• SEI CERT C Coding Standard
• C FAQ - comp.lang.c Frequently Asked Questions
• Comparison of C/POSIX standard library implementations for GNU/Linux
• Draft C11 standard
• GNU C Reference Manual
• Robert Pike's notes on programming in C

Beginner

• Tutorial on pointers
• Building C Projects
• C Programming Wikibook
• Introduction to 'fun' C
• Learning C with GDB
• POSIX Threads Programming tutorial (a little dated, but most of it is still valid and useful)
• The GNU C Programming Tutorial (online PDF)
• Templating in C

Intermediate

• 8 gdb tricks you should know
• 10 C99 tricks
• Diving into concurrency: trying out mutexes and atomics
• Introduction to OpenMP (video)
• OpenMP tutorial (for the OpenMP3 standard)
• memcpy vs memmove
• MPI tutorial
• Some unknown features or tricks in C language
• The lost art of C structure packing
• What a C programmer should know about memory
• What every C programmer should know about undefined behaviour

Advanced

• Advanced metaprogramming in C
• Quick tutorial on implementing and debugging malloc, free, calloc, and realloc
• Bit twiddling hacks
• I do not know C
• Implementing smart pointers for the C programming language
• Inline functions in C
• Metaprogramming custom control structures in C
• Solving the temporary storage problem of C macros
• Some dark corners of C
• Writing efficient C and C code optimization

Self-study courses

• C Programming Language Certified Associate preparation course

Physical

Reference

• C: A Reference Manual 5E - Full reference book for C99.
• C Pocket Reference - Concise reference book for C99.
• The C Programming Language 2E - The original book on C, by its creators.

Beginner

• C Primer Plus 6E - Complete tutorial on programming in C11.
• C Programming: A Modern Approach - Excellent book to learn the basics from C from.
• Head First C - 'Head-first' style book for learning C.

Intermediate

• 21st Century C - Very good second programming book on C.
• Understanding and Using C Pointers - In-depth resource on pointers in C.
• ZeroMQ - Book for using ZeroMQ with C.

Advanced

• Expert C Programming: Deep C Secrets - Interesting, in-depth and entertaining look at the innards of C.

Multimedia

• FFMPEG - Complete, cross-platform solution to record, convert and stream audio and video. [GNU LGPL2.1 or later] or [GNU GPL2.1 or later (some parts)]
• GStreamer - Framework for audio and visual media. [GNU LGPL2.1 only]
• lodepng - Simple PNG image decoder and encoder, requiring no other dependencies. [3-clause BSD]

Networking and Internet

• asnlc - Compiler of ASN.1 specifications into C source code. [FreeBSD]
• czmq - High-level binding for ZeroMQ. [MPL2.0]
• GNU adns - Advanced, easy-to-use, asynch-capable DNS client library and utilities. [GNU GPL3 or later]
• GNU SASL - Implementation of the Simple Authentication and Security Layer and a few common SASL mechanism. [GNU GPL3 or later]
• GnuTLS - Secure communication library, implementing SSL, TLS and DTLS. [GNU LGPL2.1 or later]
• gumbo-parser - HTML5 parsing library in C99. [Apache2.0]
• http-parser - HTTP request/response parser. [Expat]
• ldns - Library to simplify DNS programming. [3-clause BSD]
• libcurl - Client-side URL transfer library, supporting a wide range of formats. [curl license]
• LibEtPan - Mail library providing an efficient network for IMAP, SMTP, POP and NNTP. [3-clause BSD]
• libev - Yet another event loop. [FreeBSD]
• libevent - Event loop replacement for network servers. [3-clause BSD]
• libgss - Generic Security Service. [GNU GPL3 or later]
• libhttpd - Library to add basic web server capabilities to an application or embedded device. [GNU GPL2 only]
• libidn - Implementation of the Stringprep, Punycode and IDNA specifications. [GNU GPL3 or later]
• libmicrohttpd - Small C library that makes it easy to run an HTTP server as part of another application. [GNU LGPL2.1 or later]
• libsoup - GNOME HTTP client/server library. Uses GObject. [GNU LGPL2.1 only]
• lwan - Experimental, scalable, high-performance HTTP server. [GNU GPL2.1 only]
• mongoose - Embedded web server for C. [GNU GPL2.1 only]
• nanomsg - C-based implementation of ZeroMQ. [Expat]
• OpenSSL - Implementation of the SSL and TLS protocols, and also includes a cryptography library. [Dual Licensed under the OpenSSL License and the SSLeay License]
• oSip - SIP implementation in C without additional dependencies. [GNU LGPLv2.1 or later]
• pig - Linux packet crafting tool. [GPL2]
• s2n - C99 implementation of the TLS/SSL protocols, designed to be simple, fast and with security as a priority. [Apache2.0]
• socket99 - C99 wrapper for the BSD sockets API. [ISC]
• Tox - Communication platform, designed to be a Skype-killer. [GNU GPL3 only]
• twitc - Mini C library for interacting with the Twitter OAuth API. [Expat]
• librg - Library for building simple and elegant cross-platform mmo client-server solutions. [Apache2.0]

Web Frameworks

• balde - Microframework for C based on GLib. [GNU LGPLv2.1 only]
• onion - C library to create simple HTTP servers and Web Applications. [Apache2.0]
• kore - Easy to use, scalable and secure web application framework for writing web APIs in C.
• klone - KLone is a fully-featured, multiplatform, web application development framework.

Numerical

• apophenia - Library for statistical and scientific computing. [GNU GPL2.1 only]
• ATLAS - Automatically Tuned Linear Algebra Software. [3-clause BSD]
• BLAS - Basic Linear Algebra Subprograms; a set of routines that provide vector and matrix operations. [BLAS license]
• Cuba - Library for multidimensional numerical integration. [GNU LGPLv3 only]
• FFTW - The Fastest Fourier Transform in the West; a highly-optimized fast Fourier transform routine. [GNU GPL2.1 or later]
• FLINT - Fast Library for Number Theory; a library supporting arithmetic with numbers, polynomials, power series and matrices, among others. [GNU GPL2.1 or later]
• GLPK - GNU Linear Programming Kit; a package designed for solving large-scale linear programming, mixed integer programming and other related problems. [GNU GPL3 or later]
• GMP - GNU Multple Precision Arithmetic Library; a library for arbitrary-precision arithmetic. [GNU GPL2.1 only] and [GNU LGPLv3 only]
• GNU MPC - Library for complex number arithmetic. [GNU LGPL3 or later]
• GNU MPFR - Library for arbitrary-precision floating-point arithmetic. [GNU LGPL3 or later (most recent versions)] or [GNU LGPL2.1 or later (until version 2.4.x)]
• GNU MPRIA - Portable mathematics library for multi-precision rational interval arithmetic. [GNU GPL3 or later]
• GSL - The GNU Scientific Library; a sophisticated numerical library. [GNU GPL3 only]
• KISS FFT - Very simple fast Fourier transform library. [3-clause BSD]
• LAPACKE - C interface to LAPACK. [3-clause BSD]
• PARI/GP - Computer algebra system for number theory; includes a compiler to C. [GNU GPL2.1 or later]
• PETSc - Suite of data structures and routines for scalable parallel solution of scientific applications modelled by partial differential equations. [FreeBSD]
• SLEPc - Software library for the solution of large, sparse eigenvalue problems on parallel computers. [GNU LGPL3 only]
• Yeppp! - Very fast, SIMD-optimized mathematical library. [3-clause BSD]

Parallel Programming

• cchan - Small library for channel constructs for inter-thread communication. [Public domain]
• ck - Concurrency primitives, safe memory reclamation mechanisms and non-blocking data structures. [FreeBSD]
• mill - Go-style concurrency in C. [X11]
• MPICH - Another implementation of MPI. [MPICH licence]
• OpenMP - Set of C pragmas designed to allow for easy parallelization of code. [Standard (licensing not applicable)]
• OpenMPI - Message passing interface implementation. [3-clause BSD]
• PETSc - Suite of data structures and routines for scalable parallel solution of scientific applications modelled by partial differential equations. [FreeBSD]
• pth - Portable implementation for non-preemptive priority-based scheduling for multiple threads of execution. [GNU GPL3 or later]
• pthreads - The POSIX thread library. [Standard (no license applicable)]
• SLEPc - Software library for the solution of large, sparse eigenvalue problems on parallel computers. [GNU LGPL3 only]
• TinyCThread - Portable, small implementation of the C11 threads API. [zlib]

Regex

"Some people, when confronted with a problem, think 'I know, I'll use regular expressions'. Now they have two problems." - Jamie Zawinski.

• PCRE - Implementation of regexes identical to that of Perl 5. [3-clause BSD]
• SLRE - Super Light Regular Expression library; a very small implementation of a subset of Perl regex syntax. [GNU GPL2.1 only]
• TRE - POSIX-compliant, feature-full regex library. [FreeBSD]

Serialization

• binn - Binary serialization format meant to be compact, fast and easy-to-use. [Apache2.0]
• c-capnproto - Implementation of the Cap'n Proto serialization protocol. [Expat]
• cmp - Implementation of the MessagePack serialization protocol. [Expat]
• libavro - C implementation of the Avro data serialization system. [Apache2.0]
• mpack - Another implementation of the MessagePack serialization protocol. [Expat]
• netstring-c - Netstring encoder and decoder. [Public Domain]
• protobuf-c - Implementation of Google Protocol Buffer in C. [FreeBSD]
• xdr - External Data Representation; a standard for data serialization. [Standard (no license applicable)]

Check also: JSON, XML

Source Code Collections

This contains collections of small source code. If you want something big and integrated, check the Frameworks section.

• CCAN - Modelled after Perl's CPAN, this is a big collection of C code that does stuff. The full list is here. [Various free licenses]
• clib - Something of a package manager for C. Comes with a bunch of libraries of its own. [Expat]
• gnulib - Collection of common GNU code. [Various free licenses]
• libdjb - Collection of libraries doing various things. [(Apparently) Public domain]

Standard Libraries

This contains standard C libraries.

• Bionic - Google's C standard library, developed for Android. [3-clause BSD]
• dietlibc - C standard library designed for the smallest possible binaries. [GNU GPL2.1 only]
• glibc - The GNU C Library; an implementation of the C standard library. [GNU LGPL2.1 only]
• musl - Standard C library, compatible with POSIX 2008 and C11. Designed for static linking. [Expat]

String Manipulation

• bstrlib - The Better String Library. [3-clause BSD] and [GNU GPL2.1 only]
• ICU - International Components for Unicode; a library for Unicode support. [ICU license]
• libunistring - Library for manipulating Unicode strings in C. [GNU LGPL3 only]
• libgiconv - Text conversion library. [GNU LGPL2.1 only (library)] or [GNU GPL3 only (iconv program)]
• SDS - Simple Dynamic Strings; a library for handling C strings in a simpler way, but one that is compatible with normal C string functions. Available via clib. [FreeBSD]
• shoco - Compressor for small text strings. [Expat]
• smaz - Efficient string compression library. [3-clause BSD]
• utf8.h - Single header utf8 string functions. [Unlicense]

Testing

• CHEAT - Very simple unit testing framework. [FreeBSD]
• Check - Unit testing framework for C. [GNU LGPL2.1 only]
• CMock - Mock/stub generator for C. [Expat]
• cmocka - Unit testing framework with support for mock objects. [Apache2.0]
• Criterion - KISS, non-intrusive C test framework. [Expat]
• CUnit - Another unit testing framework for C. [GNU LGPL2.0 only]
• Cutest - Library for unit testing with memory leak detection (Linux, freeBSD and Windows). [GPL2]
• minunit - Minimal unit testing framework for C. [Expat]
• Unity - Simple unit testing framework for C. [Expat]

Text Editor Extensions

While practically any decent programmer's text editor supports C, there are some extensions that make it more pleasant. This is categorized by editor.

Emacs

• CEDET - Collection of Emacs Development Environment Tools; designed to provide IDE-like features to Emacs. Built-in. [GNU GPL3 or later]
• Flycheck - Modern syntax checking. For C, it can use either GCC or Clang as a back-end. [GNU GPL3 or later]
• Yasnippet - Template system, with C templates for common code snippets. [GNU GPL3 or later]

Vim

• Syntastic - Syntax checking and linting. [Do What The Fuck You Want To license]
• YouCompleteMe - Code completion engine for Vim. [GNU GPL3 only]

Tools

This is a list of useful programs to help you write and debug C code which are not editors, libraries or compilers.

• Artistic Style - Fast and small automatic source code formatter that supports C. [GNU LGPL3 only]
• address-sanitizer - Fast memory error detector. [Apache2.0]
• biicode - Modern dependency manager for C. [Expat]
• c - Compile and execute C "scripts" in one go on the command line. Also has shebang support. [Expat]
• c99sh - Run C files using hash-bang. [FreeBSD]
• CBMC - C Bounded Model Checker; a tool for verification of array bounds, pointer safety and user-specified assertions. [Original BSD]
• cdecl - Online service to translate C declarations into English and vice versa. [Public domain]
• cinclude2dot - Graphs include dependencies in a C project using Graphviz. [Any GNU GPL version (due to underspecification in the file)]
• Complexity - Tool for measuring the complexity of C source code. [GNU GPL3 or later]
• CScout - Source code analyzer and refactoring browser for collections of C programs. [GNU GPL3 only]
• DDD - Graphical front-end for a range of command-line debuggers. [GNU GPL3 or later]
• GDB - The GNU Project debugger; a debugger for C. [GNU GPL3 or later]
• Glade - RAD tool to enable quick development of GTK+ GUIs. [GNU GPL2.1 only]
• GMSL - GNU Make Standard Library; a collection of additional functionality for GNU Make. [3-clause BSD]
• GNU Global - Source code tagging tool which works with C. [GNU GPL3 only]
• gprof - Performance analysis tool. Part of GNU binutils. [GNU GPL3 or later]
• Highlight - Converts source code to formatted text with nice highlighting. [GNU GPL3 only]
• include-what-you-use - Helps find unecessary inclusions and make suggestions for fixing them. Based on LLVM/Clang (and only works with it). [NCSA]
• indent - Formats C source code automatically to make it easier to read. Also converts from one style of source to another. [GNU GPLv3 or later]
• Make - Tool which controls the generation of executables and other non-source files of a program (link to the GNU implementation). [GNU GPL3 or later]
• qo - Build system that works without a separate config file. [Expat]
• rr - Debugger that records non-deterministic executions to allow for deterministic debugging. [FreeBSD]
• tup - Very fast, file-based, cross-platform build system. [GNU GPL2.1 only]
• unifdef - Removes #ifdef and #if directives with their delimited text without touching any other part of the file. [3-clause BSD] and [FreeBSD]
• Valgrind - Range of dynamic analysis tools, including a leak checker. [GNU GPL2.1 only]

Utilities

This is a 'catch-all' category for anything that doesn't fit well anywhere else.

• ApeTagLibs - C library for working with APEv2 tags. [Expat]
• bfd - Library for manipulating binary object files. Part of GNU binutils. [GNU GPL3 or later]
• ccv - C-based/Cached/Core Computer Vision library; modern computer vision. [3-clause BSD]
• cf4ocl - The C Framework for OpenCL; a cross-platform object-oriented framework for developing and benchmarking OpenCL projects. [GNU LGPL3 (library)] or [GNU GPL3 (project code)]
• CommonMark - C implementation of the CommonMark spec. [Various free licenses]
• CException - C implementation of exceptions. [Expat]
• docopt.c - C implementation of a command-line option parser. [Expat]
• dyncall - Another foreign function interface library. [Expat]
• FANN - Fast Artifical Neural Network library; an implementation of neural networks. [GNU GPL2.1 only]
• Firm - C library that provides a graph-based intermediate representation, optimizations and assembly code generation suitable for use in compilers. Comes with an example C front-end under the same license. [GNU LGPLv2.1 only]
• gjrand - Library of random-number generation routines. [GNU GPL2.1] or [GNU GPLv3]
• GNU FreeIPMI - In-band and out-of-band IPMI implementation. [GNU GPL3 only]
• GNU gperf - Perfect hash function generator, given a list of strings. Outputs C code. [GNU GPL3 or later]
• GNU Libffcall - Collection of libraries for building foreign function interfaces. [GNU GPL3 or later]
• gperftools - Collection of utilities for measuring and improving performance. [3-clause BSD]
• hammer - Parser combinators for binary formats. [GNU GPL2.1 only]
• huffandpuff - Minimal Huffman encoder and decoder. [Public domain]
• iniparser - Parser for .ini files. [Expat]
• jemalloc - Malloc implementation that emphasizes avoidance of fragmentation and scalable concurrency support. [FreeBSD]
• jwHash - Fast hashtable implementation. [Apache2.0]
• kdtree - Simple library for working with KD-trees. [3-clause BSD]
• Kitsune - Efficient, general-purpose framework for dynamic software updating. [GNU LGPL3 or later]
• libavl - Library containing a range of self-balancing binary trees. [GNU GPL3 or later]
• libbson - BSON utility library. [Apache2.0]
• libCello - Library introducing higher-level programming to C. [3-clause BSD]
• libffi - Portable foreign-function interface library. [Expat]
• libgit2 - Pure C implementation of Git. [GNU GPL2 only, with a linking exception]
• libimobiledevice - Cross-platform protocol library to communicate with iThings. [GNU LGPLv2.1 or later (library)] or [GNU GPL2.1 or later (tools)]
• libmpv - Music-playing library. Compile with ./waf configure --disable-cplayer --enable-libmpv-shared to not have the music player. [GNU GPL2.1 or later]
• libnfc - Platform-independent Near-Field Communication library. [GNU LGPL3 only]
• libPhenom - Eventing framework for building high-scalability and high-performance systems. [Apache2.0]
• libsoundio - Library for cross-platform, real-time audio input and output. Has a range of back-ends. [Expat]
• libucl - Universal configuration library parser. [FreeBSD]
• libuv - Cross-platform asynchronous I/O. [Expat]
• libYAML - YAML 1.1 parser and emitter. [Expat]
• mpc - Parser combinator library. [FreeBSD]
• ncurses - Coloured terminal UI library. [GNU GPL3 or later]
• nope.c - C-language-based, ultra-light software platform for scalable server-side and networking applications (think node.js for C programmers). [GNU GPL2.1 only]
• pbc - Protocol buffers library. [Expat]
• rabbitmq-c - Client library for RabbitMQ. [Expat]
• Ragel - DSL for state machines that compiles to C. [GNU GPL2.1 only]
• uthash - Hash table implementation, allowing existing structures to be stored in a hash table easily. [1-clause BSD]

XML

"XML is crap. Really. There are no excuses. XML is nasty to parse for humans, and it's a disaster to parse even for computers. There's just no reason for that horrible crap to exist." - Linus Torvalds

• Expat - Stream-oriented XML parser. [Expat]
• libxml2 - Standards-compliant, portable XML parser. [Expat]
• mini-xml - Small XML reading and writing library. No dependencies aside from C standard library. [GNU LGPL2.1 with static linking exception]