This app can turn your iPhone or iPad into analog like FM synthesizer for just $2!
It can be used with MIDI keyboard so it can be considered a PRO app but it also is a nice app for beginners who want to start learning about FM synthesis.
Sonic Synth is very capable FM Synthesizer app with 3 oscillators. Every oscillator is independent and can generate 4 wave forms. Core MIDI – support for MIDI keyboards via USB – you will need MIDI keyboard and Apple’s Lightning to USB Camera Adapter
The touch keyboard is also very responsive and dynamic.
Variety of sounds can be created and even changed real time while you are playing using the setting of the 3 oscillators of the synthesizer.
Here is a link to the app: