Two oscillators, filter and ADSR
Mix sine, triangle, saw and square waves, detune them for a wide sound, and shape the tone with a resonant low-pass, high-pass or band-pass filter and its own envelope.
Online Synthesizer: Play and Shape Synth Sounds
A free online synthesizer with presets, filter, envelope and effects. Play with mouse, touch, keyboard or MIDI.
Play the online synth in three steps
No signup, no download and no plugin. It works on computers, tablets and phones.
- 01
Pick a sound
Start with one of eight presets: lead, pad, sub bass, acid bass, pluck, chiptune, strings or bell. The name shows above the oscilloscope.
- 02
Play and shape it
Click, tap or drag across the keys, use the letters A to K, or connect a MIDI keyboard. Turn the cutoff while you hold a note to hear it change.
- 03
Record and build a beat
Press Record and play your idea to the click. Open the take in the beat maker to add drums, or save it as a WAV file.
A real subtractive synth in your browser
The same building blocks as a hardware analog synth, laid out so you can see what each one does.
LFO, delay and reverb
Add vibrato or a slow filter wah with the LFO, echoes with the delay and space with the reverb. Every change is heard at once, even on notes you are holding.
Mouse, touch, keys and MIDI
Play up to twelve notes at once with your fingers, glide across the keys, use the computer keyboard, or plug in a USB MIDI keyboard with velocity.
Record into the beat maker
Record a melody or chord progression to a click, then open it in the beat maker with your sound, or save the take as a WAV file.
How a synthesizer makes sound
A synthesizer builds a sound from scratch instead of playing back a recording. This online synthesizer is a subtractive synth, the classic design behind most analog synths of the 1970s and 1980s and countless plugins today. It starts with a bright, rich waveform from the oscillators, takes parts of it away with a filter, and then shapes how loud the result is over time with an envelope.
The oscillators are the source. A sine wave is a pure tone with no overtones, soft like a flute or a sub bass. A triangle adds a few quiet overtones and sounds a little hollow. A saw wave contains every harmonic and sounds buzzy and full, which makes it the favorite for leads, strings and basses. A square wave has only the odd harmonics and gives the hollow, woody sound of clarinets and old video games.
Two oscillators make the sound bigger. Detune the second one by a few cents and the two waves drift in and out of phase, which creates the chorus like shimmer of a supersaw. Tune it an octave up or down for a thicker tone, or a twelfth up (19 semitones) for the glassy overtone of a bell.
Filter, resonance and envelopes
The filter is where most of a synth's character comes from. A low-pass filter lets the low frequencies through and cuts the highs above the cutoff, so turning the cutoff down makes the sound darker and rounder. A high-pass filter does the opposite and thins the sound out, and a band-pass keeps only a narrow band in the middle, like a telephone. Resonance boosts the frequencies right at the cutoff; turn it up and the filter starts to whistle and squelch.
An envelope describes how a value changes after you press a key. The amp envelope controls the volume with four stages: attack, decay, sustain and release, usually written as ADSR. A fast attack and no sustain make a pluck, a slow attack and a long release make a pad that swells in and fades away. The filter envelope opens the filter at the start of each note and lets it close again over the decay time, which gives basses and plucks their bite.
The LFO, a low frequency oscillator, moves something up and down slowly and steadily. Aimed at the pitch it makes vibrato; aimed at the filter it makes a slow wah or a fast wobble. The table shows how the eight presets combine these settings, so you can see why each one sounds the way it does.
| Preset | Filter cutoff | Oscillators | Attack / release | Good for |
|---|---|---|---|---|
| Classic lead | 3.20 kHz | saw + saw | 5 ms / 250 ms | Melodies and solos that cut through a mix |
| Warm pad | 1.40 kHz | saw + triangle | 900 ms / 1.80 s | Slow chords under a beat, ambient intros |
| Sub bass | 600 Hz | sine + triangle | 5 ms / 120 ms | 808 style low end for trap and hip hop |
| Acid bass | 380 Hz | saw + square | 2 ms / 100 ms | Squelchy basslines for house and techno |
| Pluck | 1.80 kHz | triangle + saw | 2 ms / 300 ms | Short arpeggios and melodies in pop and EDM |
| Chiptune | 12.0 kHz | square + square | 2 ms / 50 ms | Retro video game melodies |
| Synth strings | 2.40 kHz | saw + saw | 350 ms / 900 ms | Lush chords for ballads and lo-fi |
| Bell | 9.00 kHz | sine + sine | 2 ms / 1.60 s | Sparkling top lines and intros |
Sound design tips for beginners
Start from a preset that is close to what you want and change one control at a time. Play a note, move a slider, play the note again. After a few minutes you will know what each control does far better than from any manual. If a sound gets lost, pick the preset again to get back to the start.
For a bass that works on phone speakers as well as in a club, combine a sine or triangle for the low end with a quiet saw an octave up for presence. Keep the filter cutoff low and the release short, so fast notes do not blur together. For a lead, use two detuned saws, a medium cutoff, a little resonance, some vibrato and a touch of delay.
Pads need slow attacks of half a second or more, a long release and plenty of reverb. Play them with three or four notes at once and let the chords overlap. Plucks are the opposite: no sustain, a short decay and a strong filter envelope. Bells come from two sine waves at a wide interval with a long decay and no sustain.
From synth sound to a finished beat
A synth line rarely stands alone. Record a melody or a chord progression here and press "Open take in beat maker": your notes land on the grid of a new beat at 120 BPM, played by the beat maker's own synthesizer with settings close to your sound. Add drums, a bassline and vocals and finish the track in your browser. If you want to sketch the rhythm first, the virtual drums and the drum pad are right next door.
You do not need to know music theory to start. Stay on the white keys and every note fits the key of C major or A minor. When you want to go further, the piano chords chart shows which notes make up each chord, and the circle of fifths explains which keys sound good together.
For music teachers
Teach how sound works with a synth on the projector
Show what a waveform looks like on the oscilloscope, let students hear the difference between sine and saw, and explain overtones, filters and envelopes with a sound they can change themselves. When your class is ready to make its own music, Make a Beat gives you a whole classroom. Students join with a code and their name, no email addresses, and you set assignments, listen to what they hand in and grade it. Hosted in Germany (AI features, if switched on, send prompts to providers in the US), with a written data processing agreement on request, and every school licence starts with a free trial.
Questions about the online synthesizer
Can I play a synthesizer online for free?
Yes. This online synthesizer is free, needs no account and runs in Chrome, Edge, Firefox and Safari. Click or tap the keys, or play with your computer keyboard. You can shape the sound with two oscillators, a filter, an envelope, an LFO, delay and reverb, record what you play and save it as a WAV file.
How do I play the synth with my computer keyboard?
The middle row of letters plays the white keys: A is C, S is D, D is E, up to K for the next C. The row above plays the black keys: W, E, T, Y, U, O and P. Press Z for an octave down and X for an octave up. Hold several letters to play a chord.
Can I connect a MIDI keyboard?
Yes, in Chrome, Edge and Opera on a computer or Android. Plug in the keyboard, press "Connect MIDI keyboard" and allow access. Every key you press plays the synth with its velocity, so softer notes sound quieter. Safari on iPhone and Mac does not support Web MIDI, so use the on-screen keys there.
What do the knobs on a synthesizer do?
The oscillators make the raw tone, the filter removes high or low frequencies, and the envelope decides how the volume rises and falls each time you press a key. The LFO adds slow movement such as vibrato, and delay and reverb place the sound in a space. Change one control at a time to hear what it does.
What is ADSR on a synth?
ADSR stands for attack, decay, sustain and release, the four stages of the envelope. Attack is how fast a note fades in, decay how fast it falls to the sustain level, sustain how loud it stays while you hold the key, and release how long it rings after you let go. Short times sound plucky, long times sound soft.
How do I make a bass sound on a synthesizer?
Start from the Sub bass preset and play in the octaves below C3. Use a sine or triangle wave, keep the filter cutoff under about 600 Hz and set a fast attack with a high sustain. For an acid bass, choose a saw wave, a low cutoff, high resonance and a strong filter envelope, like the Acid bass preset.
Can I record and download what I play?
Yes. Press Record, play along to the 120 BPM click and press Stop recording. "Open take in beat maker" puts your notes and your synth sound into a new beat, ready for drums. "Save as WAV" renders the take in your browser and downloads it. You can still change the sound after recording.
Does the online synth work on a phone?
Yes. On a phone the keyboard shows one octave at a time; use the octave buttons to move up and down, and play chords with several fingers. Turn off silent mode on an iPhone, because the ringer switch also mutes sound from the browser. Headphones help to hear the bass on small speakers.
Turn your synth line into a beat
Open the free beat maker, add drums, bass and chords around your sound and record vocals in your browser.