What is a synth?
A synthesizer (or synth) is an electronic instrument that generates its sound with oscillators rather than with strings or pipes. A typical synth lead starts with a raw waveform — here a bright sawtooth — and shapes it with filters and envelopes to produce a tone that can sustain indefinitely and slide smoothly between notes. Because the sound is generated rather than sampled, a synth has a modern, electronic character unlike any acoustic instrument.
The online synth here uses a sustained sawtooth-style lead (General MIDI program 81), so every key holds a bright, steady tone as long as you press it — the sound of pop hooks, ambient pads and electronic music.
What does a synth sound like?
A synth lead sounds bright, smooth and sustained, with a clean electronic edge. Unlike the decaying acoustic voices, it does not fade on its own: a note holds for exactly as long as you keep the key down, which makes it ideal for singing, continuous melodic lines. The tone is even and uniform, so fast runs stay clear and slow melodies feel produced and modern.
That infinite sustain also makes the synth a great teacher of release control. Because a note only stops when you let go, you become sharply aware of how long you hold each note — a habit that improves your playing on every instrument.
Why play a synth online?
Hardware synthesizers range from pricey to eye-wateringly expensive, and most live inside a DAW rather than a browser. An online synth puts that modern, sustained lead one click away:
- Play pop hooks and ambient pads without buying hardware or software.
- Shift the register with Octave and Transpose to find the bright, singing range that suits a lead.
- Hold Space as a sustain pedal for long, blended synth lines.
- Record your performance and download it as an MP3, all inside your browser.
It opens instantly — no install, no sign-up. The about page explains the technology.
How to play the synth on your keyboard
Play the synth with your mouse, your touchscreen, or your computer keyboard. Middle C (C4) sits under the M key, with the surrounding notes under the surrounding keys. Because the synth sustains for as long as you hold a key, it is perfect for smooth, singing melodies — try holding a note and listening to how cleanly it rings. The highlighted keys below outline a simple pop-flavoured chord; press Play notes to hear it sustain.
Songs and scales that suit the synth
The synth shines on modern, melodic material — pop hooks, ambient pads and anything that benefits from a steady, singing line. Try Ode to Joy or Happy Birthday for a fresh, produced colour, and explore the major scales and pentatonic scales that give you raw material for synth melodies. Every scale is highlighted on the same keyboard.
The other six instruments
The synth is one of seven real instruments sharing one keyboard here. For a different mood, head back to the online piano and try the Music Box, Marimba, Harp, Rhodes or Organ — plus the piano.
Frequently asked questions
What is an online synth?
An online synth is a synthesizer you play directly in your web browser. There is nothing to install and no account to create — open the page and the instrument is ready. Each key sounds the moment you press it and sustains for as long as you hold it.
Is the online synth really free?
Yes. The synth is completely free to play, and exporting your recording as an MP3 is free too. There is no sign-up and no download.
Does it sound like a real synth?
Yes. Each note is a real sampled synth lead (General MIDI program 81) played through a SoundFont synthesizer, so you hear the same bright, sustained sawtooth-style tone as a hardware synth lead — steady for as long as you hold the key.
Can I record what I play?
Yes. Press Record, play your piece, then press Record again to stop. You can play it back and download it as an MP3. Everything is encoded inside your browser; nothing you play is uploaded.