Extempore is described as 'systems programming language designed to support the programming of real-time systems in real-time' and is an app in the Audio & Music category. There are more than 10 alternatives to Extempore for a variety of platforms, including Online / Web-based, Windows, Self-Hosted solutions, Mac and Linux. The best alternative is SuperCollider, which is both free and Open Source. Other great apps like Extempore are Sonic Pi (Free, Open Source), Synthesine (Free, Open Source), ChucK (Free, Open Source) and Nyquist (Free, Open Source).
A real time audio synthesis engine, and an object-oriented programming language specialised for music. SuperCollider was created in 1996 by James McCartney, Since version 3 it is released as free software.
Soinc Pi is a live-coding audio software. Learn to code creatively by composing, improvising or performing in an incredible range of styles from classical through to algorave. FEATURES Simple enough for computing and music lessons.
Synthesine is a web playground for synthesizing sound waves from scratch. You can use it to create sine waves, white noise, and other building blocks of sound, and then pass these through modular components to synthesize more complex sounds like bells and whistles.
Nyquist is a language and IDE for sound synthesis and music composition. It is implemented in C and C++ and runs on Win32, OSX, and Linux. Nyquist combines a powerful functional programming style with efficient signal-processing primitives.
Faust (Functional Audio Stream) is a functional programming language for sound synthesis and audio processing with a strong focus on the design of synthesizers, musical instruments, audio effects, etc.
AudioMasher is a live, in-browser audio and music programming environment. The app is based on the Sporth audio programming language by Paul Batchelor, is open-source and can be used online or via self-hosting.