Max/MSP, VCV Rack, Sonic Pi, Synthesine, Klangmeister, Pure Data, SunVox, SuperCollider, Cabbage Studio, negasonic, Wavepot, miRack, Evaluator, AudioMasher, Slang audio programming language, Faust, Csound, SOUL programming language, Gibber, Zupiter, Extempore are some alternatives to Overtone.