ModSynth allows the creation of many kinds of music synthesizers. Connect any number of oscillators, filters, delays and other synthesizer modules in a graphical editor. Then, adjust the settings of each module while playing the instrument to get a desired sound. Save as many instruments or variants of an instrument as you'd like. Eight built-in instruments are provided to help you get started.

The free version contains the following modules:
- Keyboard
- Pad (for theremin-like control)
- Oscillator
- Filter
- Envelope
- Mixer
- Amp
- Sequencer
- Delay (echo)
- Output (with scope to see the sound)

In-app purchase the full version ($4.99 US) to remove ads, expand polyphony (from 3 voices to 10), unlock advanced capabilities, and access additional synthesizer modules:
- Arpeggiator for sequential playing of the notes in a chord
- Melody for more complex sequences of notes
- MultiOsc for strings and other chorus sounds,
- Unison for more complex chorusing,
- Operator for building FM synthesis,
- PCM for sampled sounds (WAV and SF2 SoundFont files),
- Reverb for simulating room acoustics.
- Crusher for adding digital distortion.
- Compressor to combine all voices and even the sound levels
- Pan to direct sound to either left or right stereo channels.
The full version also provides the ability to record sounds to a WAV file.

ModSynth has USB MIDI support for external MIDI keyboards, including mapping of controls to CCs. It has low latency on devices supporting Android low latency (such as Nexus). All oscillators are anti-aliased, providing low distortion at higher frequencies.

A guide to using ModSynth can be found at http://bjowings.weebly.com/modsynth.html.

A VST plugin is available to run ModSynth created instruments on VST hosts on Windows. See http://bjowings.weebly.com/modsynthvst.html for the free download and instructions.