Sonic Pi!

A real time audio synthesis engine, and an object-oriented programming language specialised for music.

ChucK is a programming language for real-time sound synthesis and music creation. ChucK presents a unique time-based, concurrent programming model that's precise and expressive (we call this strongly-timed), dynamic control rates, and the ability to add and modify code on-the-fly. In addition, ChucK supports MIDI, OpenSoundControl, HID device, and multi-channel audio. It's fun and easy to learn, and offers composers, researchers, and performers a powerful programming tool for building and experimenting with complex audio synthesis/analysis programs, and real-time interactive music. »

Klangmeister is a live coding environment for the browser. It lets you design synthesisers and compose music using computer code - without having to install anything on your own computer. Klangmeister works best in Chrome, because the synthesis features that it relies on have patchy support across the other browsers.

Wavepot is a live-coding environment for creating sound and music. Build sound and music compositions on-the-fly using JavaScript and save your projects right to GitHub.

Overtone is an open source audio environment designed to explore new musical ideas from synthesis and sampling to instrument building, live-coding and collaborative jamming. We combine the powerful SuperCollider audio engine, with Clojure, a state of-the-art lisp, to create an intoxicating interactive sonic experience.

Extempore is a systems programming language designed to support the programming of real-time systems in real-time. Extempore promotes human orchestration as a meta model of real-time man-machine interaction in an increasingly distributed and environmentally aware computing context.