ReSlice - Slice your audio with an advanced, rhythmic arpeggiator and FX.
AudioKit Synth One - Free & Open-source iPhone/iPad Synth 🎹
cassini - Polyphonic Synthesizer for iPhone/iPod touch
VHS Synth - The leading free & open-source iOS/macOS music & audio dev tools. https://t.co/Ik1FiorZWH proudly powers millions of iOS app installs
nlog Synth - Professional Virtual Analogue Synthesizer ::: check nlogmusic at YouTube :::
Surge XT - Open-source subtractive-hybrid synthesizer formerly sold commercially as Vember Audio Surge.