AudioKit Synth One is a free feature-packed synth for your iPad
 

The AudioKit Synth One is a professional-level open-source synthesizer for your iPad. It has features that match or even rival the ones on iOS synths from Korg, Electro-Harmonix and Moog, which can run upwards of $25. This one, however, was created b...

https://www.engadget.com/2018/06/28/...ynth-one-ipad/