iOS Musician Apps (118) Supported Technologies is Inter-App Audio (IAA), Instrument Sounds is Keyboards

LCW-2 mono is a little complicated synthesizer based on ToyTone and implements several experimental functions.

Laplace is a physical-modeling synthesizer based on resonator synthesis that makes it easy to create bowed string, plucked string, blown pipe and metallic sounds.

Mimicking the layout of Hohner's iconic chromatic button accordions (CBA), both B-System (Bayan) and C-System, this intuitive virtual accordion is easy to play and sounds exactly like the real instrument.

Englitina is an authentic-sounding English Treble Concertina for the iPad.

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

iPhilicorda is an emulation of a vintage organ from the sixties, the Philicorda, created by the Dutch company Philips.

AudioKit Synth One is a completely free & open-source professional iOS Synthesizer. 

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

Moebius Lab is a multimorphic sound processor which contains a synth, a varispeed stereo sample player, effects and LFOs that can modulate each parameter.

The Moog Model 15 App is the Moog modular synthesizer and synthesis educational tool.

PixelWave is an experimental synth with old school pixel interface.

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

Elsa is a retro style sampling keyboard with tempo based looping.

Continua is a three-oscillator / dual-filter six-voice virtual analog synth, with fully polyphonic modulation sources and built-in custom-designed effects, for everything from complex, evolving chill-out soundscapes to New Wave synth stabs.

miRack is a Eurorack-style modular synthesizer. It aims to provide user experience and audio quality close to those of the real Eurorack hardware.

Electric Vintage is a virtual instrument based on a reproduction of a famous vintage electric piano (1976).

The Minimoog Model D App is a mobile transmutation of the world’s first portable synthesizer, the Minimoog Model D®.

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.

Agonizer is a monophonic synthesizer designed in collaboration with YouTuber and synth bass expert Jakob Haq of haQ attaQ