An online piano for when you need to hear a note right now

Most times someone looks for a piano online they don't want to practise: they want to check something. What note is that, how does this chord sound, whether the melody in their head starts on E or F. For that, opening a browser beats switching anything on.

This keyboard runs in the browser itself, with nothing to install and no sign-up, and responds to mouse, touch and computer keyboard alike. It's tuned to A4 = 440 Hz, so you can play over a track without the two fighting.

Playing with your computer keyboard

The A S D F G H J K row is the white notes, and W E T Y U the sharps, sitting where the black keys would be. It's the same layout as a piano, so what you learn here transfers. Z and X change octave, from 1 to 7, which is what lets you drop into bass territory or climb for a melody without losing your place.

From playing chords to understanding why they sound like that

A piano lets you hear harmony, but it won't tell you why one progression works and another doesn't. Chord Cosmos is built for exactly that: assembling progressions on the circle of fifths and hearing them. And if what you need is the key or tempo of a track you already have as a file, the BPM and key finder does it for you.

Frequently asked questions

Do I need to install anything or sign up?

No. It plays straight in the browser with Web Audio — no plugins, no account, no downloads. On mobile it works the same by tapping the on-screen keys.

How do I play it with my computer keyboard?

A S D F G H J K are the white notes and W E T Y U the sharps, matching the layout of a real piano. Z and X move you down and up an octave, from 1 to 7.

Is it in tune?

Yes, at the standard A4 = 440 Hz reference — the same one a tuned acoustic piano and any tuner use. You can play along to a track without it drifting.

What are the six sounds for?

Piano and E. Piano for practising chords and harmony, which is the most common use. Organ and Strings sustain while you hold the key, so they're good for hearing how the voices of a chord stack up. Synth and Marimba have sharper attacks and suit rhythm and articulation work.

Does it replace a real keyboard?

For checking a note, working out a progression or practising chords when your keyboard isn't in front of you, yes. For technique, no: without weighted keys or velocity sensitivity you can't train the dynamics of your hand, and that's half of playing piano.