A playable synthesizer in your browser
This online synthesizer is a classic subtractive synth: two oscillators and a noise source feed a resonant filter, two envelopes shape the volume and the filter over time, and an LFO adds vibrato, wah, tremolo or auto-pan. Unison stacks up to seven detuned copies of every note for big leads and pads, and a delay, reverb and drive finish the sound. Fourteen presets — pads, basses, plucks, brass, strings, organ, chiptune and bells — get you started, and every knob is yours to change.
Play it with the mouse, with several fingers on a touch screen, with your computer keyboard or with a USB MIDI keyboard in Chrome, Edge or Opera. Press Record to capture a performance and save it as an MP3 or WAV, or keep just the notes as a MIDI file.
How to use the Online Synthesizer
- Press any key on the on-screen keyboard, or use the computer keys: Z S X D C V… play the lower octave and Q 2 W 3 E R… the one above. The arrows (or the buttons) move the keyboard by an octave.
- Choose a Preset, then turn the controls: oscillator waves and tuning, filter cutoff and resonance, the attack, decay, sustain and release of the envelopes, the LFO and the effects.
- Hold Space or press Hold to sustain notes like a piano pedal. Press Connect MIDI keyboard to play from a hardware keyboard.
- Type a name and press Save to keep a sound as your own preset in this browser.
- Press Record, play, then press Stop. Your take is rendered as an MP3 or WAV to listen to and download, and the notes can be saved as a .mid file.
Online Synthesizer features
Two oscillators + noise
Sine, triangle, saw and square waves with octave, semitone and fine tuning, plus white noise for breath and percussion.
Resonant filter
Low-pass, high-pass or band-pass with resonance, key tracking and its own ADSR envelope (±4 octaves).
Unison and glide
Up to 7 detuned voices per note spread across the stereo field; a mono mode with legato glide for basses and leads.
LFO
Vibrato, filter wah, tremolo or auto-pan at 0.1–20 Hz with four wave shapes.
Delay, reverb, drive
An echo with feedback, a room, hall or plate reverb and a warm saturation stage, followed by a safety limiter.
Record to MP3, WAV or MIDI
Takes are re-rendered from your notes and knob moves at full quality, so there are no dropouts.
How subtractive synthesis works
A subtractive synth starts with a waveform that is rich in harmonics and carves the tone with a filter. A sawtooth has every harmonic and sounds bright and brassy, a square has only odd harmonics and sounds hollow, a triangle is softer and a sine is pure. The low-pass filter removes harmonics above the cutoff; raising the resonance boosts the frequencies right at the cutoff for a vocal or squelchy edge.
An envelope describes how a value changes after you press a key: attack is the time to reach full level, decay the time to fall to the sustain level, which holds while the key is down, and release the fade after you let go. Short attack and decay with no sustain make a pluck; slow attack and long release make a pad. The filter envelope does the same for the cutoff, which is how the “wow” of a synth bass or brass stab is made.
Sound recipes
| Sound | Try this |
|---|---|
| Fat bass | Saw + square an octave lower, low-pass at 300–500 Hz, filter envelope +2 octaves with a short decay, Mono with a little glide |
| Pad | Two saws slightly detuned, Unison 5, slow attack and release, reverb mix 30–40 % |
| Pluck | Square or saw, sustain 0 %, decay 300–500 ms, filter envelope +3 octaves, delay 25 % |
| Wobble | LFO to filter cutoff at 2–4 Hz with high depth and resonance |
| Chiptune | Square wave, filter open, short release, a touch of vibrato |
Good to know
- Up to 16 notes sound at once; the oldest is released when you go past that. Mono mode plays one note and glides between them while keys overlap.
- Sound starts only after you press a key; nothing plays on its own. Notes are released if you switch tabs.
- Web MIDI works in Chrome, Edge and Opera on computers and Android. Safari and iPhone/iPad browsers do not support it; the on-screen and computer keys still work.
- Takes can be up to 5 minutes long. Knob moves made while recording are rendered from the next note on; a change of reverb type or length mid-take is not.
Online Synthesizer FAQ
Is this online synthesizer free?
Yes. There is no sign-up and no limit on playing, saving presets or downloading your recordings.
Can I play it with my computer keyboard?
Yes. The bottom letter row (Z, X, C…) plays from the lowest C on screen and the row starting with Q from the C above, with the black keys on the row above each. The arrow keys change the octave.
Does it work with a MIDI keyboard?
Yes, in Chrome, Edge and Opera. Press Connect MIDI keyboard and allow access; velocity, the sustain pedal and pitch bend are used.
How do I record and download what I play?
Press Record, play, then press Stop. Choose MP3 or WAV, listen to the result and press Download. You can also download the notes as a MIDI file to use in a DAW.
Why is there a short delay when I play?
Browsers add some output latency, usually 10–40 ms. Wired headphones and a desktop browser give the lowest delay; Bluetooth headphones add more.
Can I save my own sounds?
Yes. Type a name and press Save; the sound appears under Your presets in this browser.