Intertakt is an interval timer for HIIT, Tabata and rounds, built with Flutter around one engineering bet: sound is the primary output, the screen is just the remote. Voice cues and countdown beeps play over the user's own music with independent volumes, and the plan works with the screen off — sessions survive calls and app switches and resume from the exact second. Free tier unlimited: 0 ads, ∞ sessions, 0 accounts. Premium is a one-time purchase, not a subscription: custom plans, history, JSON export. Offline-first. Live on Google Play today; iOS waitlist open — one email when it ships.