MaxMSP

Max is a visual programming language for music and multimedia developed and maintained by San Francisco-based software company Cycling '74. During its 20-year history, it has been widely used by composers, performers, software designers, researchers, and artists for creating innovative recordings, performances, and installations.

The Max program itself is highly modular, with most routines existing in the form of shared libraries. An API allows third-party development of new routines (called "external objects"). As a result, Max has a large userbase of programmers not affiliated with Cycling '74 who enhance the software with commercial and non-commercial extensions to the program. Because of its extensible design and graphical interface (which in a novel way represents the program structure and the GUI as presented to the user simultaneously), Max is widely regarded as the lingua franca for developing interactive music performance software.