Hi HN, I’m a solo developer from Austria. After 18 months, I built SkiCoach - an AI ski coaching app based on a simple philosophy: your data is yours. The Black Box Concept: Like an airplane black box, the app records everything - GPS, accelerometer, gyroscope, barometer - but nothing ever leaves your device. No cloud sync. No accounts. No tracking. Full AI processing happens on-device. What it does: ∙ Analyzes ski technique via phone sensors (phone stays in pocket) ∙ Real-time audio coaching while skiing ∙ Technique score 0-100 per run ∙ Auto-detects when you start skiing (>10km/h + altitude >1000m) ∙ Works completely offline (no signal needed on mountain) Tech: ∙ Flutter (iOS + Android) ∙ TensorFlow Lite for on-device AI ∙ 4 languages (EN/DE/FR/IT) Business model: One-time €19.99 purchase. No subscription. I believe ski apps shouldn’t cost €25/year forever. More on the philosophy: theskiblackbox.com Live on iOS, Android this week: skicoach.app Would love feedback from skiers and privacy-focused folks.