iOS Musician Apps (117) Supported Technologies is Inter-App Audio (IAA), Instrument Sounds is Keyboards

Flynth is a synthesizer by Fingerlab, designed for musicality and easy use.

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

Colossus Piano sets a new standard in terms of realism, detail and overall quality of piano sounds on your iPad, iPhone and iPod touch.

Play with the sound of a full cathedral organ, created by award-winning sound designer Kurt Ader.

The second best sounding piano app in the App Store (after "Colossus Piano")!

Combine 3 oscillators and a noise envelope to produce bright 80s-style synths, deep rich bass, punchy kicks and snares, a variety of screaming leads, and even breathy percussion.

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.

LayR is a polyphonic, multi-timbral synthesizer for iPad and iPhone, delivering up to 256 voices of rich, multi-layered and textured sounds.

Poison-202 is a professional Vintage Midi Synthesizer.

Galileo Organ 2 is a tonewheel and transistor organ app.

Kauldron is a synth with new modeling technology, combined with features help you create aggressive synth sounds full of rich analog textures with the fewest knob tweaks.

Harness the enormous power of 8 polyphonic synths: meet KASPAR Supersynthesizer.

With EGSY01 you can create sounds, from modern ones to vintage analog ones, working with arpeggiator, step sequencer and FM, addictive and subtractive synthesis.

FM TiNES is an electric piano library dedicated to the most beautiful FM electric pianos ever made.

Neo-Soul Keys® Studio 2 is the next evolution in electric piano sounds and effects from Gospel Musicians, which features a complete architecture overhaul using our new Pure Synth® structure and licensed VKFX effects.

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

Tardigrain is a granular synthesizer. Sounds are created by taking smaller fragments of a sample and playing them back in a non linear fashion, with settings for grain size, direction, step size and more.

A matrix-controlled arpeggiator designed to play with your thumbs.

Synthesizer specially designed for creating and experiments with ambient soundscapes in wide range from noises to melodic instruments and everything in between.