PortAudio is an open-source computer library for audio playback and recording. It is a cross-platform library, so programs using it can run on many different computer operating systems, including Windows, Mac OS X, and Linux. PortAudio supports Core Audio, ALSA, and MME, DirectSound, ASIO, and WASAPI on Windows. Like other libraries whose primary goal is portability, PortAudio is written in the C programming language. It has also been implemented in the PureBasic, and Lazarus/Free Pascal languages. PortAudio is based on a callback paradigm, similar to JACK and ASIO.
PortAudio is part of the PortMedia project, which aims to provide a set of platform-independent libraries for music software. The free audio editor Audacity uses the PortAudio library, and so does JACK on the Windows platform.