参考：https://github.com/fffaraz/awesome-cpp

Standard Libraries

C++ Standard Library - including STL Containers, STL Aglorithm, STL Functional, etc.

• C++ Standard Library - A collection of classes and functions, which are written in the core language and part of the C++ ISO Standard itself.
• Standard Template Library - The Standard Template Library (STL).
• C POSIX library - A specification of a C standard library for POSIX systems.
• ISO C++ Standards Committee - ISO/IEC JTC1/SC22/WG21 - The C++ Standards Committee.website

Frameworks

C++ generic frameworks and libraries.

• Apache C++ Standard Library - A collection of algorithms, containers, iterators, and other fundamental components. [Apache2]
• ASL - Adobe Source Libraries provides peer-reviewed and portable C++ source libraries. [MIT]
• Boost  - A large collection of generic C++ libraries. [Boost] website
• BDE - The BDE Development Environment from Bloomberg Labs. [MIT]
• Cinder - A community-developed, free and open source library for professional-quality creative coding. [BSD]
• Cxxomfort - A small, header-only library that backports to C++03 some of the nifty C++11 goodies. [MIT]
• Dlib  - A general purpose cross-platform C++ library designed using contract programming and modern C++ techniques. [Boost]
• EASTL - Public part of EA-STL. [BSD]
• ffead-cpp - Framework for Enterprise Application Development. [Apache2]
• Folly - An open-source C++ library developed and used at Facebook. [Apache2]
• JUCE - An all-encompassing C++ class library for developing cross-platform software. [Core-Module: ISC, Rest: GPL2/GPL3/Commercial] website
• libPhenom - libPhenom is an eventing framework for building high performance and high scalability systems in C. [Apache2]
• LibSourcey - C++11 evented IO for real-time video streaming and high performance networking applications. [LGPL]
• LibU - A multiplatform utility library written in C. [BSD]
• Loki - A C++ library of designs, containing flexible implementations of common design patterns and idioms. [MIT]
• MiLi - Minimal headers-only C++ Library. [Boost]
• openFrameworks - An open source C++ toolkit for creative coding. [MIT]
• Qt  - A cross-platform application and UI framework. [LGPL]
• Reason - A cross platform framework designed to bring the ease of use of Java, .Net, or Python to developers who require the performance and strength of C++. [GPLv2]
• ROOT - A set of OO frameworks with all the functionality needed to handle and analyze large amounts of data in a very efficient way. Used at CERN. [LGPL]
• STLport - An exemplary version of STL. [Free]
• STXXL - Standard Template Library for Extra Large Data Sets. [Boost]
• Ultimate++ - A C++ cross-platform rapid application development framework. [BSD]
• Windows Template Library - A C++ library for developing Windows applications and UI components. [Public]
• Yomm11 - Open multi-methods for C++11. [Boost]

Artificial Intelligence

• btsk - Game Behavior Tree Starter Kit. [zlib]
• Evolving Objects - A template-based, ANSI-C++ evolutionary computation library which helps you to write your own stochastic optimization algorithms insanely fast. [LGPL]
• Neu - A C++ 11 framework, collection of programming languages, and multipurpose software system designed for: the creation of artificial intelligence applications. [BSD]

Asynchronous Event Loop

• Boost.Asio - A cross-platform C++ library for network and low-level I/O programming. [Boost]
• libev - A full-featured and high-performance event loop that is loosely modelled after libevent, but without its limitations and bugs. [BSD and GPL]
• libevent - An event notification library. [BSD]
• libuv - Cross-platform asychronous I/O. [BSD]

Audio

Audio, Sound, Music, Digitized Voice Libraries

• FMOD - An easy to use crossplatform audio engine and audio content creation tool for games. [Free for non-commercial/Commercial]
• Maximilian - C++ Audio and Music DSP Library. [MIT]
• OpenAL - Open Audio Library - A crossplatform audio API. [BSD/LGPL/Commercial]
• Opus - A totally open, royalty-free, highly versatile audio codec. [BSD]
• Speex - A free codec for free speech. Obsoleted by Opus. [BSD]
• Tonic - Easy and efficient audio synthesis in C++. [Unlicense]
• Vorbis - Ogg Vorbis is a fully open, non-proprietary, patent-and-royalty-free, general-purpose compressed audio format. [BSD]

Biology

Bioinformatics, Genomics, Biotech

• libsequence - A C++ library for representing and analyzing population genetics data. [GPL]
• SeqAn - Algorithms and data structures for the analysis of sequences with the focus on biological data. [BSD/3-clause]
• Vcflib - A C++ library for parsing and manipulating VCF files. [MIT]
• Wham - Structural variants (SVs) in Genomes by directly applying association tests to BAM files.

Compression

Compression and Archiving Libraries

• bzip2 - A freely available, patent free, high-quality data compressor. [BSD]
• doboz - Compression library with very fast decompression. [zlib]
• PhysicsFS - A library to provide abstract access to various archives. It is intended for use in video games, and the design was somewhat inspired by Quake 3's file subsystem. [zlib]
• KArchive - A library for creating, reading, writing and manipulating file archives like zip and tar. It also provides transparent compression and decompression of data, using formats like gzip, via a subclass of QIODevice. [LGPL]
• LZ4 - Extremely Fast Compression algorithm. [BSD]
• LZHAM - Lossless data compression library with a compression ratio similar to LZMA but with much faster decompression. [BSD]
• LZMA  - The default and general compression method of 7z format. [LGPL]
• LZMAT - An extremely fast real-time lossless data compression library. [GPL]
• miniz - Single C source file Deflate/Inflate compression library with zlib-compatible API, ZIP archive reading/writing, PNG writing. [Unlicense]
• Minizip - Zlib with latest bug fixes that supports PKWARE disk spanning, AES encryption, and IO buffering. [zlib]
• Snappy - A fast compressor/decompressor. [BSD]
• ZLib - A very compact compression library for data streams. [zlib]
• ZZIPlib - Provides read access on ZIP-archives. [MPL/LGPL]

Concurrency

Concurrency and Multithreading

• Boost.Compute - A C++ GPU Computing Library for OpenCL. [Boost]
• Bolt - A C++ template library optimized for GPUs. [Apache2]
• C++React - A reactive programming library for C++11. [Boost]
• Intel TBB - Intel Threading Building Blocks. [GPLv2 with runtime exception]
• Libclsph - An OpenCL based GPU accelerated SPH fluid simulation library. [MIT]
• OpenCL - The open standard for parallel programming of heterogeneous systems.
• OpenMP - The OpenMP API.
• Thrust - A parallel algorithms library which resembles the C++ Standard Template Library (STL). [Apache2]
• HPX - A general purpose C++ runtime system for parallel and distributed applications of any scale. [Boost]
• VexCL - A C++ vector expression template library for OpenCL/CUDA. [MIT]

Containers

• C++ B-tree - A template library that implements ordered in-memory containers based on a B-tree data structure. [Apache2]
• Hashmaps - Implementation of open addressing hash table algorithms in C++. [MIT]

Cryptography

Cryptography and Encryption Libraries

• Bcrypt - A cross platform file encryption utility. Encrypted files are portable across all supported operating systems and processors.
• BeeCrypt
• Botan - A crypto library for C++. [BSD-2]
• Crypto++ - A free C++ class library of cryptographic schemes. [Boost]
• GnuPG - A complete and free implementation of the OpenPGP standard. [GPL]
• GnuTLS - A secure communications library implementing the SSL, TLS and DTLS protocols. [LGPLv2.1]
• Libgcrypt
• libmcrypt
• LibreSSL - A free version of the SSL/TLS protocol forked from OpenSSL in 2014. [?]
• libsodium - P(ortable|ackageable) NaCl-based crypto library, opinionated and easy to use. [ISC]
• LibTomCrypt - A fairly comprehensive, modular and portable cryptographic toolkit. [WTFPL]
• Nettle - A low-level cryptographic library. [LGPL]
• OpenSSL - A robust, commercial-grade, full-featured, and Open Source cryptography library. [Apache]
• Tiny AES128 in C - A small and portable implementation of the AES128 ECB encryption algorithm implemented in C. [PublicDomain]

Database

Database Libraries, SQL Servers, ODBC Drivers, and Tools

• hiberlite - C++ Object-relational mapping for sqlite3. [BSD]
• Hiredis - A minimalistic C client library for the Redis database. [BSD]
• LevelDB - A fast key-value storage library. [BSD]
• LMDB - Very fast embedded key/value store with full ACID semantics. [OpenLDAP]
• MySQL++ - A C++ wrapper for MySQL's C API. [LGPL]
• RocksDB - Embedded key-value store for fast storage from facebook. [BSD]
• SQLite - A completely embedded, full-featured relational database in a few 100k that you can include right into your project. [PublicDomain]

Debug

Debugging Libraries, Memory Leak and Resource Leak Detection, Unit Testing

• Boost.Test - Boost Test Library. [Boost]
• Catch - A modern, C++-native, header-only, framework for unit-tests, TDD and BDD. [Boost]
• CppUnit - C++ port of JUnit. [LGPLv2]
• CTest - The CMake test driver program. [BSD]
• googletest - Google C++ Testing Framework. [BSD]
• ig-debugheap - Multiplatform debug heap useful for tracking down memory errors. [BSD]
• libtap - Write tests in C. [GPLv2]
• MemTrack - Tracking memory allocations in C++.
• microprofile - Profiler with web-view for multiple platforms. [PublicDomain]
• minUnit - A minimal unit testing framework for C written using only 2 macros. [PublicDomain]
• Remotery - Single C File Profiler with Web Viewer. [Apache2]
• UnitTest++ - A lightweight unit testing framework for C++. [MIT/X Consortium license]

Game Engine

• Cocos2d-x - A multi-platform framework for building 2d games, interactive books, demos and other graphical applications. [Commercial?]
• Grit - Community project to build a free game engine for implementing open world 3D games. [MIT]
• Irrlicht - An open source high performance realtime 3D engine written in C++. [zlib]
• Polycode - Open-Source Framework for creating games in C++ (with Lua bindings). [MIT]

GUI

Graphic User Interface

• CEGUI - Flexible, cross-platform GUI library.
• FLTK - Fast, light, cross-platform C++ GUI toolkit. [GPLv2]
• GTK+ - A multi-platform toolkit for creating graphical user interfaces. [LGPL]
• gtkmm - The official C++ interface for the popular GUI library GTK+. [LGPL]
• imgui - Immediate Mode Graphical User Interface with minimal dependencies. [MIT]
• libRocket - libRocket is a C++ HTML/CSS game interface middleware. [MIT]
• MyGUI - Fast, flexible and simple GUI. [MIT]
• Ncurses - A terminal user interfaces. [MIT]
• QCustomPlot - Qt plotting widget without further dependencies. [GPLv3]
• Qwt - Qt Widgets for Technical Applications. [Own based on LGPL]
• QwtPlot3D - A feature-rich Qt/OpenGL-based C++ programming library, providing essentially a bunch of 3D-widgets. [zlib]
• OtterUI - OtterUI is a User Interface development solution for embedded systems and interactive entertainment software. [MIT]
• PDCurses - Public domain curses library with both source code and pre-compiled library available. [PublicDomain]
• wxWidgets - A C++ library that lets developers create applications for Windows, Mac OS X, Linux and other platforms with a single code base. [Own LGPL]

Graphics

• bgfx - A cross-platform rendering library. [BSD]
• Cairo - A 2D graphics library with support for multiple output devices. [LGPLv2 or Mozilla MPL]
• Horde3D - A small 3D rendering and animation engine. [EPL]
• magnum - C++11 and OpenGL 2D/3D graphics engine. [MIT] website
• Ogre 3D  - A scene-oriented, real-time, flexible 3D rendering engine (as opposed to a game engine) written in C++. [MIT]
• OpenSceneGraph - An open source high performance 3D graphics toolkit. [OSGPL]
• Panda3D - A framework for 3D rendering and game development for Python and C++. [BSD]
• Skia - A complete 2D graphic library for drawing Text, Geometries, and Images. [bSD] webpage
• urho3d - Cross-platform rendering and game engine. [Many different, mostly MIT]

Image Processing

• Boost.GIL - Generic Image Library.
• CImg - A small, open source, C++ toolkit for image processing. [Own LGPL or GPL]
• CxImage - An image processing and conversion library to load, save, display, transform BMP, JPEG, GIF, PNG, TIFF, MNG, ICO, PCX, TGA, WMF, WBMP, JBG, J2K images. [zlib]
• FreeImage - An open source library that supports popular graphics image formats and others as needed by today's multimedia applications. [GPLv2 or GPLv3]
• GDCM - Grassroots DICOM library.
• ITK - An open-source, cross-platform system for image analysis. [Apache 2.0 from ITK 4.0]
• Magick++ - ImageMagick program interfaces for C++. [Apache 2.0]
• MagickWnd - ImageMagick program interfaces for C. [Apache 2.0]
• OpenCV  - Open source computer vision. [BSD]
• tesseract-ocr - An OCR engine. [Apache 2.0]
• VIGRA - A generic C++ computer vision library for image analysis. [MIT X11]
• VTK - Open-source, freely available software system for 3D computer graphics, image processing and visualization. [BSD]

Internationalization

• gettext - GNU `gettext'. [GPLv2]
• IBM ICU - A set of C/C++ and Java libraries providing Unicode and Globalization support. [ICU]
• libiconv - An encoding conversion library between different character encodings. [GPL]

JSON

• frozen - JSON parser and generator for C/C++. [GPL & GPLv2]
• Jansson - C library for encoding, decoding and manipulating JSON data. [MIT]
• jbson - jbson is a library for building & iterating BSON data, and JSON documents in C++14. [Boost]
• JeayeSON - A very sane (header only) C++ JSON library. [BSD]
• JSON++ - A JSON parser in C++. [MIT]
• json-parser - Very low footprint JSON parser written in portable ANSI C. [BSD]
• json11 - A tiny JSON library for C++11. [MIT]
• jute - Very simple C++ JSON Parser. [PublicDomain]
• libjson - A JSON parser and printer library in C. easy to integrate with any model. [LGPL]
• libjson - Lightweight JSON library. [?]
• PicoJSON - A header-file-only, JSON parser serializer in C++. [BSD]
• qt-json - A simple class for parsing JSON data into a QVariant hierarchy and vice versa. [GPLv3]
• QJson - A qt-based library that maps JSON data to QVariant objects. [LGPLv2]
• RapidJSON  - A fast JSON parser/generator for C++ with both SAX/DOM style API. [MIT]
• YAJL - A fast streaming JSON parsing library in C. [ISC]

Logging

• Boost.Log - Designed to be very modular and extensible. [Boost]
• easyloggingpp - Single header only C++ logging library. [MIT] website
• Log4cpp - A library of C++ classes for flexible logging to files, syslog, IDSA and other destinations. [LGPL]
• templog - A very small and lightweight C++ library which you can use to add logging to your C++ applications. [Boost]

Machine Learning

• Caffe - A fast framework for neural networks. [BSD]
• CCV - C-based/Cached/Core Computer Vision Library, A Modern Computer Vision Library. [BSD]
• mlpack - A scalable c++ machine learning library. [LGPLv3]
• OpenCV  - Open Source Computer Vision Library. [BSD] website
• Recommender - C library for product recommendations/suggestions using collaborative filtering (CF). [BSD]
• SHOGUN - The Shogun Machine Learning Toolbox. [GPLv3]
• sofia-ml - The suite of fast incremental algorithms for machine learning. [Apache2]

Math

• Armadillo - A high quality C++ linear algebra library, aiming towards a good balance between speed and ease of use. The syntax (API) is deliberately similar to Matlab. [MPL2]
• blaze - high-performance C++ math library for dense and sparse arithmetic. [BSD]
• ceres-solver - C++ library for modeling and solving large complicated nonlinear least squares problems from google. [BSD]
• CGal - Collection of efficient and reliable geometric algorithms. [LGPL&GPL]
• cml - free C++ math library for games and graphics. [Boost]
• Eigen - A high-level C++ library of template headers for linear algebra, matrix and vector operations, numerical solvers and related algorithms. [MPL2]
• GMTL - Graphics Math Template Library is a collection of tools implementing Graphics primitives in generalized ways. [GPLv2]
• GMP - A C/C++ library for arbitrary precision arithmetic, operating on signed integers, rational numbers, and floating-point numbers. [LGPLv3 and GPLv2]

Multimedia

• GStreamer - A library for constructing graphs of media-handling components. [LGPL]
• LIVE555 Streaming Media - Multimedia streaming library using open standard protocols (RTP/RTCP, RTSP, SIP). [LGPL]
• libVLC - libVLC (VLC SDK) media framework. [GPL]
• QtAv - A multimedia playback framework based on Qt and FFmpeg to write a player easily. [LGPL] website
• SDL  - Simple DirectMedia Layer. [zlib]
• SFML  - Simple and Fast Multimedia Library. [zlib]

Networking

• ACE - An OO Network Programming Toolkit in C++. [?MIT?]
• Boost.Asio  - A cross-platform C++ library for network and low-level I/O programming. [Boost]
• Casablanca - C++ REST SDK. [Apache2]
• cpp-netlib - A collection of open-source libraries for high level network programming. [Boost]
• Dyad.c - Asynchronous networking for C. [MIT]
• libcurl - Multiprotocol file transfer library. [MIT/X derivate license]
• Mongoose - Extremely lightweight webserver. [GPLv2]
• Muduo - A C++ non-blocking network library for multi-threaded server in Linux. [BSD]
• net_skeleton - TCP client/server library for C/C++. [GPLv2]
• nope.c - A C language-based ultra-light software platform for scalable server-side and networking applications. Think node.js for C programmers. [GPLv2]
• Onion - HTTP server library in C designed to be lightweight and easy to use. [Apache2/GPLv2]
• POCO  - C++ class libraries and frameworks for building network- and internet-based applications that run on desktop, server, mobile and embedded systems. [Boost] website
• RakNet - A cross platform, open source, C++ networking engine for game programmers. [BSD]
• Tufão - An asynchronous web framework for C++ built on top of Qt. [LGPLv2]
• WebSocket++ - C++/Boost Asio based websocket client/server library. [BSD]
• ZeroMQ - High-speed, modular asynchronous communication library. [LGPL]

Physics

Dynamics simulation engines

• Box2D - A 2D physics engine for games. [BSD-like]
• Bullet - A 3D physics engine for games. [zlib] website
• Chipmunk - A fast and lightweight 2D game physics library. [MIT] website
• LiquidFun - A 2D physics engine for games. [BSD-like]
• Newton Dynamics - An integrated solution for real time simulation of physics environments. [zlib]
• ODE - Open Dynamics Engine - An open source, high performance library for simulating rigid body dynamics. [BSD&LGPL]
• ofxBox2d - openFrameworks wrapper for Box2D. [BSD-like]
• Simbody - High-performance C++ multibody dynamics/physics library for simulating articulated biomechanical and mechanical systems like vehicles, robots, and the human skeleton. [Apache2]

Robotics

• MOOS-IvP - A set of open source C++ modules for providing autonomy on robotic platforms, in particular autonomous marine vehicles.
• MRPT - Mobile Robot Programming Toolkit. [BSD]
• PCL - Point Cloud Library is a standalone, large scale, open project for 2D/3D image and point cloud processing [BSD] website
• Robotics Library (RL) - A self-contained C++ library for robot kinematics, motion planning and control. [BSD]
• RobWork - A collection of C++ libraries for simulation and control of robot systems. [Apache2]
• ROS - Robot Operating System provides libraries and tools to help software developers create robot applications. [BSD]

Scientific Computing

• FFTW - A C library for computing the DFT in one or more dimensions. [GPL]
• GSL - GNU scientific library. [GPL]

Scripting

• ChaiScript - An easy to use embedded scripting language for C++. [BSD] website
• Lua - A minimal and fast scripting engine for configuration files and basic application scripting. [MIT]
• luacxx - C++11 API for creating Lua bindings. [MIT]
• SWIG - A wrapper/interface Generator that let you link your c++ code to Javascript, Perl, PHP, Python, Tcl and Ruby. [GPL/Output not licensed]
• V7 - An embedded JavaScript engine. [GPLv2]
• V8 - A fast JavaScript engine by Google that can be embedded into any C++ application. [BSD]

Serialization

• Cap'n Proto - Fast data interchange format and capability-based RPC system. [MIT]
• cereal - A C++11 library for serialization. [BSD]
• FlatBuffers - A Memory efficient serialization library. [Apache2]
• MessagePack - Efficient binary serialization format "like JSON" for C/C++. [Apache2] website
• protobuf - Protocol Buffers - Google's data interchange format. [BSD]
• protobuf-c - Protocol Buffers implementation in C. [BSD]
• SimpleBinaryEncoding - encoding and decoding application messages in binary format for low-latency applications. [Apache2]
• Thrift - Efficient cross-language IPC/RPC, works between C++, Java, Python, PHP, C#, and many more other languages. Originally developer by Twitter. [Apache2]

Video

• libvpx - VP8/VP9 Codec SDK. [BSD]
• FFmpeg - A complete, cross-platform solution to record, convert and stream audio and video. [LGPLv2/GPL2]
• libde265 - Open h.265 video codec implementation. [LGPL] website
• OpenH264 - Open Source H.264 Codec. [BSD] website
• Theora - A free and open video compression format. [BSD]

Virtual Machines

• CarpVM - "interesting" VM in C. Let's see how this goes. [GPLv3]
• MicroPython - Aims to put an implementation of Python 3.x on a microcontroller. [MIT]
• TinyVM - A small, fast, lightweight virtual machine written in pure ANSI C. [MIT]

Web Application Framework

• Civetweb - Provides easy to use, powerful, C/C++ embeddable web server with optional CGI, SSL and Lua support. [MIT]
• CppCMS - A Free High Performance Web Development Framework (not a CMS). [LGPLv3]
• Crow - Crow is C++ micro web framework (inspired by Python Flask). [BSD]
• Kore - ultra fast and flexible web server / framework for web applications developed in C. [ISC]
• libOnion - lightweight library to help you create webservers in C programming language. [LGPLv3]
• QDjango - A web framework written in C++ and built on top of the Qt library. Where possible it tries to follow django's API, hence its name. [LGPL]
• Wt - A C++ library for developing web applications. [GPL/Commercial]

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 - An XML parser library written in C. [MIT]
• Libxml2 - The XML C parser and toolkit of Gnome. [MIT]
• libxml++ - An XML Parser for C++. [LGPLv2]
• PugiXML - A light-weight, simple and fast XML parser for C++ with XPath support. [MIT]
• RapidXml - An attempt to create the fastest XML parser possible, while retaining useability, portability and reasonable W3C compatibility. [Boost]
• TinyXML - A simple, small, minimal, C++ XML parser that can be easily integrating into other programs. [zlib]
• TinyXML2 - A simple, small, efficient, C++ XML parser that can be easily integrating into other programs. [zlib]
• TinyXML++ - A completely new interface to TinyXML that uses MANY of the C++ strengths. Templates, exceptions, and much better error handling. [MIT]
• Xerces-C++ - A validating XML parser written in a portable subset of C++. [Apache2]

Miscellaneous

Useful libraries or tools that don't fit in the categories above or maybe just not categorised yet

• C++ Format - Small, safe and fast formatting library for C++. [BSD]
• casacore - A set of c++ core libraries derived from aips++. [LGPL]
• cxx-prettyprint - A pretty printing library for C++ containers. [Boost]
• DynaPDF - An easy-to-use PDF generation library. [Commercial]
• gcc-poison - A simple header file for developers to ban unsafe C/C++ functions from applications.
• googlemock - A library for writing and using C++ mock classes. [BSD]
• HTTP Parser  - A http request/response parser for C. [MIT]
• libcpuid - A small C library for x86 CPU detection and feature extraction. [BSD]
• libevil - The Evil License Manager. [GPLv3]
• libusb - A universal USB library which allows for portable access to USB devices. [LGPLv2]
• PCRE - A regular expression C library inspired by the regular expression capabilities in Perl. [BSD]
• Remote Call Framework - Inter-process communication framework for C++. [GPLv2/Commercial]
• Scintilla - A free source code editing component. [MIT]
• Serial Communication Library - Cross-platform, Serial Port library written in C++. [MIT]
• SDS - Simple Dynamic Strings library for C. [BSD]
• SLDR - Super Light DNS Resolver. [GPLv2/Commercial]
• SLRE - Super Light Regular Expression library. [GPLv2/Commercial]
• Stage - Mobile robot simulator. [GPLv2]
• VarTypes - A feature-rich, object-oriented framework for managing variables in C++ / Qt4. [LGPL]
• ZBar - A barcode scanner library, which allows to scan photos/images/video streams for barcodes and return their value. [LGPLv2]
• CppVerbalExpressions - C++ regular expressions made easy. [MIT]
• QtVerbalExpressions - This Qt lib is based off of the C++ VerbalExpressions library. [MIT]
• PHP-CPP - A library to build PHP extensions with C++. [Apache2] website
• Better String - An alternative to the string library for C which is more functional and does not have buffer overflow overrun problems. Also includes a C++ wrapper. [BSD, GPLv2]

Software

Software for creating a development environment.

Compiler

List of C/C++ compilers

• Clang - Developed by Apple.
• GCC - GNU Compiler Collection.
• Intel C++ Compiler - Developed by Intel.
• LLVM - Collection of modular and reusable compiler and toolchain technologies.
• Microsoft Visual C++ - MSVC, developed by Microsoft.
• Open WatCom - Watcom C, C++, and Fortran cross compilers and tools. [Sybase Open Watcom Public License]
• TCC - Tiny C Compiler. [LGPL]

Online Compiler

List of online C/C++ compilers

• codepad - An online compiler/interpreter, and a simple collaboration tool.
• CodeTwist - A simple online compiler/interpreter, where you can paste your C, C++ or Java code and execute it online and see results.
• coliru - Online compiler/shell with support for various C++ compilers.
• Compiler Explorer - An interactive compiler with assembly output available.
• CompileOnline - Compile and Execute C++ online on Linux.
• Ideone - An online compiler and debugging tool which allows you to compile source code and execute it online in more than 60 programming languages.

Debugger

List of C/C++ debuggers

• Comparison of debuggers - A list of Debuggers from Wikipedia.
• GDB - GNU Debugger.
• Valgrind - A tool for memory debugging, memory leak detection, and profiling.
• x64_dbg - An open-source x64/x32 debugger for windows.

Integrated Development Environment

List of C/C++ nominal IDEs.

• AppCode - an IDE for Objective-C, C, C++, and JavaScript development built on JetBrains’ IntelliJ IDEA platform.
• CLion - Cross-platform C/C++ IDE from JetBrains. In pre-release/early access stadium.
• Code::Blocks - A free C, C++ and Fortran IDE.
• CodeLite - Another cross-plaform, free C/C++ IDE. [GPLv2 with an exception for plugins]
• Dev-C++ - A portable C/C++/C++11 IDE.
• Eclipse CDT - A fully functional C and C++ IDE based on the Eclipse platform.
• Geany - Small, fast, cross-platform IDE. [GPL]
• IBM VisualAge - A family of computer integrated development environments from IBM.
• Irony-mode - A C/C++ minor mode for Emacs powered by libclang.
• KDevelop - A free, open source IDE.
• Microsoft Visual Studio - An IDE from Microsoft.
• NetBeans - An IDE for developing primarily with Java, but also with other languages, in particular PHP, C/C++, and HTML5.
• Qt Creator  - A cross-platform C++, JavaScript and QML IDE which is part of the SDK for Qt.
• rtags - A c/c++ client/server indexer with for integration with emacs based on clang.
• Xcode - Developed by Apple.
• YouCompleteMe - YouCompleteMe is a fast, as-you-type, fuzzy-search code completion engine for Vim.

Build Systems

• Bear - A tool to generate compilation database for clang tooling.
• Biicode - Simple, file-based dependency manager.
• CMake - Cross-platform free and open-source software for managing the build process of software using a compiler-independent method. [BSD]
• CPM - A C++ Package Manager based on CMake and Git.
• FASTBuild - High performance, open-source build system supporting highly scalable compilation, caching and network distribution.
• Ninja - A small build system with a focus on speed.
• Scons - A software construction tool configured with Python scipt.
• tundra - High-performance code build system designed to give the best possible incremental build times even for very large software projects.
• tup - File-based build system that monitors in the background for changed files.
• Premake - A tool configured with lua scipt to generate project files for Visual Studio, GNU Make, Xcode, Code::Blocks, and more across Windows, Mac OS X, and Linux.

Static Code Analysis

List of tools for improving quality and reducing defects by code analysis

• Cppcheck - A tool for static C/C++ code analysis. - source
• include-what-you-use - A tool for use with clang to analyze includes in C and C++ source files.
• OCLint - A static source code analysis tool to improve quality and reduce defects for C, C++ and Objective-C. - source
• Clang Static Analyzer - A source code analysis tool that finds bugs in C, C++, and Objective-C programs.
• List of tools for static code analysis - A list of tools for static code analysis from Wikipedia.

Resources

Various resources, such as books, websites, and articles for improving your C++ development skills and knowledge.

API Design

• Beautiful Native Libraries
• Designing Qt-Style C++ APIs

Articles

Fantastic C/C++ related articles.

• CppCon 2014 Speaker Materials - Speaker materials from CppCon 2014.
• C++Now 2014 Presentations - Presentation materials presented at C++Now 2014.
• C++Now 2013 Presentations - Presentation materials presented at C++Now 2013.
• C++Now 2012 Presentations - Presentation materials presented at C++Now 2012.

Books

Fantastic C/C++ related books.

• The C++ Annotations - An in-depth guide on C++, intended for people with a good knowledge of C who want to make the transition to C++.
• Free C Books - vhf/free-programming-books/C.
• Free C++ Books - vhf/free-programming-books/C++.
• The Definitive C++ Book Guide and List - A collection of quality books and an approximate skill level.

Coding Style

• google-styleguide - Style guides for Google-originated open-source projects.
• Google C++ Style Guide
• GNU Coding Standard

Talks

• CppCon Talks  - The C++ conference.
• Quick game development with C++11/C++14 - CppCon 2014 talk by Vittorio Romeo.

Videos

Fantastic C/C++ related videos.

• Awesome C Programming Tutorials in Hi Def [HD] - A collection of detailed C Programming Language Tutorials for Beginners and New Programmers.
• C++ - by VoidRealms.
• C++ Qt Programming - by VoidRealms.
• C++ Programming Tutorials Playlist - TheNewBoston Official Buckys C++ Programming Tutorials Playlist.
• C++ Programming Tutorials from thenewboston - These are all of thenewboston's C++ programming tutorials.
• C++ GUI with Qt Playlist - Official Playlist for thenewboston C++ GUI with Qt tutorials.
• C Programming Tutorials - All of TheNewBoston's C programming tutorials are right here.
• Bo Qian's playlist - Boost Library, C++ Standard Library, Modern C++, Advanced C++, Advanced STL, ...

Websites

Useful C/C++ related websites.

• Standard C++  - News, Status & Discussion about Standard C++.
• CppCon - The C++ Conference.
• C++ reference - C++98, C++03, C++11, C++14 reference.
• cplusplus.com - The C++ Resources Network.
• Meeting C++

Weblogs

Useful C/C++ related weblogs.

• Coding For Speed - Coding For Speed DOT COM, Less Execution Time.
• Eric Niebler
• Sticky Bits
• Paul Fultz II's Blog

Other Awesome Projects

Collection of useful codes, snippets, ...

• algorithms - Algorithms & Data Structures in C++.
• c-algorithms - C algorithms library.
• C/C++ Awesome Pack - Contains some awesome c++ codes, packed in one.

Other Awesome Lists

Other amazingly awesome lists

• lists - List of (awesome) lists curated on GitHub.
• awesome-awesomeness - A curated list of awesome awesomeness.
• awesome - A curated list of awesome lists.
• free-programming-books - List of Freely Available Programming Books.
• papers-we-love - Papers from the computer science community to read and discuss.
• awesome-php - Awesome PHP libraries, resources and shiny things.
• awesome-python - Awesome Python frameworks, libraries and software.
• awesome-sysadmin - Awesome open source sysadmin resources.
• awesome-talks - A lot of screencasts, recordings of user group gatherings and conference talks.
• github-cheat-sheet - A list of cool features of Git and GitHub.
• ToolsOfTheTrade - Tools of The Trade, from Hacker News.
• cheatsheets.org - The largest collection of reference cards for developers.
• cheat-sheets.org - All cheat sheets, round-ups, quick reference cards, quick reference guides and quick reference sheets in one page.
• thefreecountry.com - A collection of free programming resources, free webmasters' resources, free security resources and free utilities.