This online piano tutor works from screenshots and photos, and it never touches your file or your instrument. The limit is said out loud because it is the method: it cannot hear you play. It reads a photo of both hands on the keys, the page of the score or lead sheet in front of you, your metronome screen, and what you report in words, such as which note lands late or where the hands stop lining up.
A session is a loop. You show the state, it gives exactly one action, you do it, you show it again: what I see, do this, send the next photo. It knows what to look at, the bench height against your forearm, the knuckle bridge, the thumb on its side, and the five beginner mistakes a photo gives away. You get an interface map of the keyboard and the notation, the session protocol, and a lesson arc from posture to a piece played through. If anything hurts, it stops and sends you to a teacher or a doctor.
The same file works in Claude, ChatGPT and Gemini. Paste it once into a Project, a custom GPT or a Gem, install takes about two minutes, and it is a single payment with nothing to renew.