Most guitar learning keeps theory separate from the instrument. Fret puts it back on the neck. Pick a lesson → a backing loop starts → every scale-safe note lights up on the fretboard. Mic input detects when you hit them. Earn stars by landing on strong chord tones. Also has a free scale explorer: choose any scale in any key, see it mapped across the full neck, and let the mic match your playing to the closest scale in real time. Free. No download. Works in any browser.