PortAudio Alternatives

OpenAL Soft is an LGPL-licensed, cross-platform, software implementation of the OpenAL 3D audio API. It's forked from the open-sourced Windows version available originally from openal.org's SVN repository (now defunct).

JUCE is a wide-ranging C++ class library for building rich cross-platform applications and plugins for all the major operating systems.

"Wwise® is the most advanced, feature-rich interactive sound engine for games, bar none. Whether you're an indie or a multi-million dollar production, Wwise will work for you." - Audiokinetic.com

RtAudio is a set of C++ classes that provide a common API for realtime audio input/output across Linux, Macintosh OS-X and Windows operating systems. RtAudio significantly simplifies the process of interacting with computer audio hardware.

FMOD is a proprietary audio library that plays music files of diverse formats on many different operating system platforms, used in games and software applications to provide audio functionality.

KFR is built for developers who need a powerful toolkit for audio and DSP applications. The framework is packed with ready-to-use C++ classes and functions for various DSP tasks from high-quality filtering to small helpers to improve development speed.

SoLoud is portable - the c/c++ code base is written in portable way, and the code has been used on various platforms including windows, osx, linux, as well as android and even ps4. (I'm not responsible for many of the platforms, though, and for licensing reasons, ps4 code is...

Elements C++ GUI is a modern C++ (esp. C++14 and C++17) UI library. Featuring resolution independence and HDPI support, with modularity as another focal point, the library is made for general purpose use while also covering everything needed for audio plugin development.

AudioKit is the leading open-source audio framework. It powers millions of app installs. AudioKit allows developers to quickly add professional audio functionality to iOS, macOS, and Apple Watch apps.