iOS Musician Apps (132) Supported Technologies is Inter-App Audio (IAA), Instrument Type is Synth

Tera Synth is a Modular Analog Synthesizer.

Vox Unit is a vocoder. You speak in the microphone, you play on the keyboard, and choir and vocal effects are produced.

This is a synthesizer designed specifically for making Dubstep, DNB and EDM lead bass/synth.

Droneo is a synthesizer which drones with various timbres and precise intonations that blur the distinction between tones, timbres and chords. Its drone is great for meditation, centering, and calming,  walking and biking, but also can be set up for discordant noise and insect-like buzzing and chirping.

Phawuo is a monophonic virtual-analog synth with "dirty" oscillators. Good for bass sound and effects.

Arpeggist is a MIDI Note arpeggiator with a very flexible step matrix editor for programming and a unique “rolling dice” random arpeggio generator.

PixiTracker 1BIT is a simple and fun tool to quickly create musical sketches, chiptunes and experiments with TRUE 1-BIT SOUND (like on old microcomputers).
No musical knowledge required.

An app which is a faithful digital re-creation of their circa 1980 analog cult-classic, The MINI-SYNTHESIZER.

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.

AnalogKit lets you play, share, and build synths and effects in an incredible digital playground.

SKIIID is a new drum-synthesizer with 4 expressive pads and the possibility to morph between them.

A creative bass music synth sequencer for electro melodies or dirty phat & funky acid techno basslines.

S-Modular is a semi modular synthesizer for your iPad.

Turning your iPad in to a classic sounding theremin.

SynthDrum Pads 100% synthesized signal path, Virtual Analog Drum Synthesiser, with 32 step sequencer.

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

Esoteric Synth is a unusual generator of synthetic sound events. The synthesis is based on 5 oscillators which are intersected through an multiple amplitude modulation and multiple frequency modulation making  an high sound variability. This App is suitable to generate complex sound textures, glitches, noises, sound clouds, sound drones, point sounds and more.

With the special lightweight version of SynthScaper LE you can easily create and modify your own multi-timbral pads and atmospheric soundscapes.

Hexaglyphics is a 13-bit noise generator with an interface based on an original alphabet for hexadecimal values.

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