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

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.

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).

SpectrumGen is a spectral synthesizer with a simple and effective user interface.

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

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

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

Zillidrone is a sample-based groovebox for creating, performing and interacting with 32-step sequences for snares, kicks, hi-hats, sampler and two multioscillator synthesizers.

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.

mood is a personal interpretation of the legendary Analog Synthesizer by Eugenio Giordani

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

GarageBand is a DAW by Apple.

iMini is a recreation of the legendary synthesizer created by Bob Moog in 1971, one of most iconic synthesizers of all time.

When a punchy, fat sound is demanded, look no further. iProphet recreates the unique sound of the classic Sequential Circuits Prophet VS synthesizer.

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.

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.

Quanta is a six-voice granular synthesizer for iOS11+ in both standalone (with Inter-App Audio) and AudioUnit V3 formats.

AudioKit Bass 808 Synth is perfect for earth-shaking sub bass lines and creating your own custom electronic drum sounds – It’s the ultimate tool for creating your own 808 Kick basses!

Epic 64-voice Virtual Analog / PCM iPad Synth. Inspired by the Digital Synths of the 80s and 90s.

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