Most piano apps teach you to hit the right key at the right moment. That gets you through a song. It also makes you sound like a typewriter.

Chordzy teaches the other half, which is playing like a person. You learn songs by ear first, and the sheet music catches up with you. Real tutors are expensive and most apps are poor teachers, so Chordzy gives you the kind of feedback a tutor would.

Plug a MIDI keyboard into your computer and Chordzy grades every note you play against the music on screen. At the start, you mostly want to know what is correct. Once you play well, it grades the finer things too, like dynamics and swing.

A first session is short. You pick a song, and Chordzy cuts it into small chunks. You play each hand on its own, then both hands together, and then you build up speed.

If you have never played, start with Adult Beginner Piano. It is a free course built around one song, Twinkle, Twinkle, Little Star, played on your own piano.

If you already play, the free sheet music runs from easy piano songs for beginners to Beethoven. Music theory covers the scales and triad chords of every major and minor key, and the exercises drill them on your keyboard.

The free tools run in the browser with nothing to install: a metronome, a virtual piano, a chord finder, the circle of fifths and sight reading practice.

You do not need an account to start. The desktop app adds jams, where you play with a friend over the internet. The ideas behind all of it are in educational theory.