iOS Musician Apps (321) Supported Technologies is Inter-App Audio (IAA), Type is Instrument

Respiro Wind-Synth for iOS is a free standalone app (IAA) and AUv3 plugin synthesizer giving you access to six fully functional wind instruments for your device.

Mynth is the new intuitive and powerful synthesizer by Fingerlab.

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

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

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.

Chorus Sampler is an advanced, easy-to-use sampler.  It features sample recording, cropping, audio importing/exporting, looping, and configurable per sample effects.

Jamm Pro is the anticipated evolution of Ninja Jamm, the original touch controlled beat app. Easy to use but deep, Jamm Pro includes Ninja Jamm users most requested feature: the ability to load your own samples.

SynthMaster One iPhone is KV331 Audio's first full blown synth app for iPhone. It's a powerful wavetable synth with an intuitive workflow. With its simple layout, rich wavetable/waveform content and inspiring factory presets library, designing new sounds with SynthMaster One iPhone is a joy.

SDS-x is a "nine pads" style drum module that lets you easily use samples alongside your drum kit.

Expand your musical horizon by playing Arabic, Armenian, Balkan, Greek, Klezmer, Persian & Turkish sounds, scales and rhythms.

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.

SK-51 is an all-in-one keyboard inspired by the Casio SK-1 (and his brother the SK-5), a 8-bit lo-fi keyboard from the 80’s, with sampling features and onboard drum machine.
Called the poor man's sampler at the time, this keyboard was a real instrument and has been used by many major artists such as Fatboy Slim, Portishead, Autechre and Nine Inch Nails.

Triqtraq LE is a free limited edition of the critically acclaimed music app Triqtraq - Jam Sequencer.

The Beat Station is a rhythm machine for practicing guitar, bass, keyboard, or any type of instrument, and also brings to production and live performance the ease of not requiring live drums and a drummer.

Piano For You is suitable for professional musicians as well as for learning piano.

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.

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.

Gestrument Pro takes everything we loved about Gestrument and improves on its original functionality while introducing a host of new features such as multi-touch, recordable automations, advanced scale editing and our unique system of highly tweakable modular generators that define the pitches and rhythms.

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

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