duolingo for telling tones apart

Tonal languages use pitch to distinguish words that otherwise sound identical. tonolingo synthesizes each tone contour live — no audio files — and drills your ear on Mandarin, Vietnamese, and Cantonese, plus a warm-up on abstract rise/fall/dip shapes. Earn XP, keep your streak, get certified. Riffing on the "duolingo for X" thread that started with @norvid-studies.