Online Synthesizer
This online synthesizer is a playable two-oscillator synth in your browser. Shape it with a resonant filter, an ADSR envelope and delay, switch between presets, and play with your mouse or computer keyboard. Nothing to install.
Presets
Play with your mouse or the ASD…K keys — WETYU are the black keys. Z/X change octave.
How the Online Synthesizer works
This online synthesizer is a classic subtractive synth: two oscillators generate a rich waveform — sine, triangle, sawtooth or square — which you can detune and mix, then a resonant low-pass filter carves away harmonics to shape the tone. A filter envelope sweeps the cutoff on each key press, while the ADSR envelope controls how the volume attacks, decays, sustains and releases. A feedback delay adds space at the end. Start from a preset and tweak from there, and watch the oscilloscope respond as you play. Use your mouse, a touchscreen or the computer keyboard — it is fully polyphonic. Everything runs on your device with the Web Audio API, so nothing is installed or uploaded. Next, play melodies on the Online Piano, build chords with the Chord Finder, or sequence a beat on the Drum Machine.
Frequently Asked Questions
How do I play the online synthesizer?
Click or tap the on-screen keys, or use your computer keyboard: the A S D F G H J K row plays the white keys and W E T Y U play the black keys, with Z and X shifting down or up an octave. It is polyphonic, so you can hold several notes at once. Pick a preset to start, then shape the sound with the oscillator, filter, envelope and delay controls.
What do the filter and envelope controls do?
The low-pass filter removes the higher harmonics above its cutoff, and resonance emphasises the frequencies right at the cutoff for a sharper, more vocal tone; the filter envelope sweeps the cutoff each time you press a key. The ADSR envelope shapes the volume over time — attack is how quickly the note fades in, decay and sustain set the held level, and release is how long it takes to fade out after you let go. The two envelopes are set separately, so a note can open bright and stay quiet, or the other way round.
Is this a subtractive synthesizer?
Yes — this synth is subtractive by design. It uses two oscillators to generate a harmonically rich waveform such as a sawtooth or square, and a resonant low-pass filter then carves away harmonics to shape the timbre, with envelopes controlling how the filter and volume change over the life of each note. A delay adds space at the end of the chain.
Does it work on a phone and is anything installed?
The synthesizer works on phones and tablets — tap the keys to play — and there is nothing to install. All the sound is generated in your browser with the Web Audio API, so nothing is uploaded or recorded, and after the page loads the synthesizer also works offline. Nothing is installed and there is no app to download — it is a web page. The layout adapts to a small screen and the keys respond to touch, including sliding across them to play legato. Bear in mind that mobile browsers block audio until you interact with the page, so tap once before you expect to hear anything.
Last updated: