iOS Musician Apps (128) Supported Technologies is Inter-App Audio (IAA), Instrument Sounds is Keyboards

SynthMaster One iOS is the mobile version of KV331 Audio's SynthMaster One software synthesizer.

Syndt is a polyphonic synthesizer with a lot of possibilities.

SunVox is a small and fast cross-platform modular synthesizer with pattern based sequencer (tracker).

Multilevel Interactive Sound Synthesizer. Up to 240 Frequency Modulation Oscillators or simple Wavetable Additive.

SpringSound is a physical-modeling audio synthesizer that produces sounds by simulating interactions and vibrations of a set of activators and masses connected to springs.

SpectrumGen is a spectral synthesizer with a simple and effective user interface.

With this instrument you can transform any sound into a playable musical instrument via a technique known as Granular Synthesis.

ShockWave is a monophonic Synthesizer designed to bring modular style workflow to the world of iOS & AUv3 plugins.

Shape is a polyphonic synthesiser allowing the user to draw the shape of the oscillator waveform.

Ribbons is an extraordinarily fun and expressive musical instrument for iPad.

Redshrike is a polyphonic synthesizer that combines a resonator designed to make more complicated sound creation and subtraction synthesis with an FM oscillator that creates violent distortion.

Ravenscroft Grand is a piano sampler.

Quanta is a six-voice granular synthesizer for iOS11+ in both standalone (with Inter-App Audio) and AudioUnit V3 formats.

Pure Synth® Platinum is a full-blown rompler/synthesizer for your iOS device. Neither the synth engine or the sample engine is an afterthought: Both engines are fully capable and feature-rich. The romper section contains a well rounded assortment of analog, synth, string, digital, and acoustic instruments.

Pure Piano is a professional, multi-sampled concert grand piano with a unique Morph Pad that allows you to explore a multitude of sounds ranging from mellow and intimate tones to surreal, cinematic textures.

For all creatures in the ocean of sound - Sonic textures from other worlds, Analog signature sounds,  Cut-through-the-mix leads and silkily smooth pads.

Poison-202 is a professional Vintage Midi Synthesizer.

PixelWave is an experimental synth with old school pixel interface.

A Simple Ad-Free Piano-like Musical Keyboard. Easy to Play, Good Response and Small Application Size. Just Play the Instrument. The app doesn't use sampled real sounds but use FM synthesis. It sounds like piano though it's false.