Max/MSP, VCV Rack, Overtone, NimSynth, Axiom synthesizer, SynthEdit, Pure Data, Hexen Modular Synthesizer, SunVox, Reaktor, SuperCollider, Cabbage Studio, Voltage Modular, miRack, Automatonism, DCubix Twist, Wren modular synthesizer, Softube Modular, SoloRack are some alternatives to Zupiter.