GuitarOS exists to answer one question every time you pick up a guitar: what should I practice today? Most people who quit the guitar don't quit because it's too hard — they quit because they open a browser tab, get fifteen results for "how to play guitar," and close the laptop before they've played a single note. Decision fatigue kills more guitar habits than difficult chords do.
So GuitarOS does the deciding for you. Open it, and there is exactly one button: Start today's practice. Behind that button is a short, structured session — a warm-up, a technique you haven't touched in a while, progress on a song you're learning, and something to apply it to — built to fit whatever time you told it you have. You press Next until you're done. That's the whole interaction model.
It would be easy to bolt a language model onto this and call it "AI-powered practice coaching." We didn't, and won't. The session you get is built by a small set of explicit, readable rules — not a model, not a recommendation API, not anything probabilistic. Give it the same profile and the same date twice, and it hands you the exact same session both times. That's not a limitation; it's the point. A practice tool should be predictable enough that you trust it without having to double-check it, and simple enough that a beginner guitarist can understand why it picked what it picked, not just accept a black box.
Concretely, the engine walks four rules in order: start with a short warm-up; surface whichever technique has gone the longest without practice; give real time to the song you're actively learning; and fill whatever's left with something that matches your genres, favoring whatever you've practiced least recently. Every session screen shows the reason each block was chosen, in plain language, right next to it.
GuitarOS doesn't host or re-upload anyone's lessons, tabs, or recordings. Every lesson entry is metadata — a title, a difficulty rating, a set of chords, a tempo — that points out to the actual creator's video on YouTube, or to a tab on Ultimate Guitar or Songsterr. When you watch a lesson video inside GuitarOS, you're watching it embedded directly from YouTube, with the original creator credited and the original view counted on their channel. The chord diagrams you see are drawn by GuitarOS itself from chord names (which aren't anyone's intellectual property) — nothing here is a copy of someone else's transcription.
GuitarOS started as a personal tool: a way to stop spending the first five minutes of every practice session scrolling instead of playing. It's built and maintained by one person, for anyone with the same problem. If something's broken or a song is missing, the contact page goes straight to a real inbox.