iOS Musician Apps (115) Supported Technologies is Inter-App Audio (IAA), Instrument Sounds is Keyboards

Based on Hohner's iconic Corona Classic diatonic accordion, this virtual accordion app plays in all five of the most popular tones: EAD (Mi), FBbEb (Fa), GCF (Sol), ADG, and BbEbAb.

Baervaag brings FM synthesis to the masses! An easy to use but still tweakable synthesizer, accessible to everyone.

Syndt is a polyphonic synthesizer with a lot of possibilities.

The concert quality piano app.

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.

Electro-Harmonix, a pioneer since 1968 in the field of sound effects pedals for musicians, has produced an app which is a faithful digital re-creation of their circa 1980 analog cult-classic, The MINI-SYNTHESIZER.

Nanologue boasts a wide scope of inspiring sounds and professional sound effects, sporting a straightforward multi-touch interface and a great-sounding monophonic synthesizer.

Designed to deliver authentic dub sounds and effects, iTALIZER at it's heart is a monophonic synthesizer paired with an authentic tape echo emulation.

iSEM is a recreation of the classic 1974 Oberheim SEM (Synthesizer Expander Module), one of the world's first self-contained synthesizer modules and the first to bear the "Oberheim Electronics" name.

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.

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

SynthQ is a subtractive synthesizer with a customizable interface.

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

Fed up with standardized presets and instruments? Feel lost in overcomplex filters and effects? Don’t wanna sound like everyone else? BLEASS is just the right instrument for you: it unleashes your inner musical creativity by bringing music production and performance to its very core: play, perform, compose beats and melodies in a new yet intuitive way thanks to its multitrack sequencer, synthesizer and drum machine.

Portable Music Production Studio : create beats, compose whole tracks, sample, record, sequence, perform, mix and arrange your own music.

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.

AutoArp turns your iPhone (or iPod Touch) into a musical instrument that is halfway between a traditional auto-harp zither and an arpeggiated analogue-style synth.

Mellowsound is an emulation of a legendary instrument, a keyboard sampler from the 60s used by many famous artists like the Beatles, David Bowie, Radiohead and many others, this mythic instrument is called The Mellotron.

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

Modulin is a customizable synthesizer. It allows for unique personal expression while providing a wide spectrum of visual feedback.