Tool
Online Synthesizer
A synthesizer you play and shape in the browser. Pick a sound to start from, then move the wave, the filter and the envelope and hear it change under your fingers. Free, no download, no account.
Slow Pad
Slow, glowing chords that fill a room.
No MIDI keyboard? Play with your computer keys: bottom rows are the lower octave, top rows the higher one. Hold Shift to sustain. ← → octave, ↑ ↓ semitone.
The controls
Wave
The raw shape the sound starts as, before anything is done to it.
Filter
Cutoff takes the brightness off the top. Resonance makes the frequency right at the cutoff ring, which is the classic synth “wah”. Sweep is how far the cutoff opens by itself each time you press a key: turn it down to nothing and Cutoff alone decides how bright the sound is.
Envelope
How the loudness moves across one note: how fast it arrives, how it falls, where it settles while you hold, and how long it takes to go once you let go.
Nothing here is saved and nothing is uploaded. Reload the page and every control is back where it started.
What a synthesizer actually is
A synthesizer builds sound instead of recording it. There is no tape and no recorded instrument inside.
Every sound above takes the same three steps, in the same order.
- An oscillator makes a raw wave. Sine is pure and flute-like; sawtooth is bright and buzzy.
- A filter takes part of that wave away, usually the top.
- An envelope decides how the sound behaves across one note, from press to silence.
Start from a sound, then ruin it
Every preset above is a sound that ships on HitJam, and each one is a normal recipe rather than a locked patch.
Load one and take a single control to its extreme. Pull the cutoff down and the brightest sound on the list goes muffled. Push the attack up and a sharp pluck turns into a slow pad.
That is the fastest way to learn what a control does: move one thing, on a sound you already know, until the change is obvious.
The filter is the one you will reach for
Think of the cutoff as a line drawn across the sound. Everything above the line is removed.
Slide it down and the sound loses its top: bright becomes warm, then muffled, then almost nothing. Slide it up and the whole sound comes back.
- Cutoff: where that line sits.
- Resonance: makes the frequency right at the line ring. This is the classic synth "wah".
- Sweep: how far the line opens by itself each time you press a key. Turn it to nothing and Cutoff alone decides the brightness.
The envelope is the shape of one note
Press a key on a piano and the sound arrives instantly, then fades. Bow a violin and it swells in. Same notes, different shape.
Four controls draw that shape, and they are the same four on every synth ever made.
- Attack: how long the sound takes to reach full volume. Short is a pluck; long is a pad that swells.
- Decay: how it falls once it has got there.
- Sustain: the level it holds while your finger stays down.
- Release: how long it takes to disappear after you let go.
Play it with your keys, or a real MIDI keyboard
Nothing needs configuring. The letter keys are already a keyboard: the bottom rows are the lower octave, the top rows the higher one. Hold Shift to sustain, and use the arrow keys to move up and down.
A MIDI keyboard is better, because it sends how hard you hit each key and the synth answers it. Plug it in with a USB cable in Chrome, Edge or Firefox, then allow MIDI once when the browser asks.
Questions people ask
- Is this a real synthesizer?
- Yes. The sound is built from oscillators, a filter and envelopes, calculated as you play rather than played back from a recording. That is what makes a synthesizer a synthesizer, and it is the same engine the rest of the site runs on.
- Do I need to install anything?
- No. It runs in the browser on the computer or phone you are reading this on. There is no plugin, no account and no download, and nothing you play is uploaded anywhere.
- Can I use my MIDI keyboard?
- Yes, in Chrome, Edge or Firefox on a computer. Plug the keyboard in with a USB cable, allow MIDI once when the browser asks, and your own keys play the synth with real velocity. Safari has no MIDI support on any device.
- What do the controls actually do?
- Wave picks the raw shape the sound starts as. Cutoff takes brightness off the top and resonance makes the frequency at the cutoff ring. The four envelope controls shape the loudness of one note: how fast it arrives, how it falls, where it sits while held, and how long it takes to fade once you let go.
- Can I save a sound I like?
- Not yet. Reload the page and every control is back where it started. Saving would need an account, and this page deliberately does not have one.
- Is it free?
- Yes, and there is no paid tier behind it. Nothing here is a trial of something else.