Godot Engine – Multi-platform 2D and 3D game engine

Bitcoin Core integration/staging tree

Dear ImGui: Bloat-free Graphical User interface for C++ with minimal dependencies

An open-source C++ library developed and used at Facebook.

A modern formatting library

Cocos2d-x is a suite of open-source, cross-platform, game-development tools utilized by millions of developers across the globe. Its core has evolved to serve as the foundation for Cocos Creator 1.…

DOOM Open Source Release

Cross-platform, graphics API agnostic, "Bring Your Own Engine/Framework" style rendering library.

A fast and easy-to-use status bar

Cap'n Proto serialization/RPC system - core tools and C++ library

a small build system with a focus on speed

Luanti (formerly Minetest) is an open source voxel game-creation platform with easy modding and game creation

ZeroMQ core engine in C++, implements ZMTP/3.1

mawww's experiment for a better code editor

OpenGL Mathematics (GLM)

Log file navigator

A C++ library for interacting with JSON.

Crow is very fast and easy to use C++ micro web framework (inspired by Python Flask)

Mumble is an open-source, low-latency, high quality voice chat software.

an efficient feature complete C++ bittorrent implementation

Cinder is a community-developed, free and open source library for professional-quality creative coding in C++.

Doom 3 GPL source release

Ultra fast JSON decoder and encoder written in C with Python bindings

Low-latency machine code generation

A beautiful stack trace pretty printer for C++

A lightweight game engine written in modern C++

Elements C++ GUI library

Farbrausch demo tools 2001-2011

A high-performance REST toolkit written in C++

Libre music sequencer for desktop and mobile platforms