Hello Sun is a skin-first vitamin D tracking partner that helps you safely get enough vitamin D from sun exposure while avoiding sunburns. Built around a weekly rhythm philosophy rather than daily perfection, Hello Sun recognizes that vitamin D is stored in your body and real life is messy.

Key Features
Real-Time Safety & Tracking • Start sun exposure sessions with a reliable timer that continues running even when your phone is backgrounded or the app is closed • Get real-time vitamin D estimates (IU) during active sessions • Receive conservative burn risk warnings and countdown timers to keep your skin safe • Adaptive acclimation system learns from your sun exposure patterns and adjusts safe limits to match your real-world tolerance—no more inaccurate conservative limits for experienced users

Weekly Progress Philosophy • Track your rolling 7-day vitamin D status instead of daily perfection • See combined totals from sun exposure and supplements in one place • Monitor progress through meaningful weekly insights, not guilt-based streaks

Smart Planning • View 7-day UV forecasts with best window recommendations for optimal sun exposure • Plan your sunshine around weather, schedule, and lifestyle • Get personalized recommendations based on your skin type, location, SPF, and coverage

Privacy & Ethics • No ads, ever—especially not during active sessions • No data selling or creepy tracking • All safety features are free—skin health is never paywalled • Local-first storage with optional cloud sync (Plus feature)

Comprehensive Tracking • Log vitamin D supplements alongside sun exposure for complete daily totals • View 30 days of history (unlimited with Plus) • Track patterns and consistency over time • Winter Mode automatically adapts during low-UV months

Hello Sun Plus unlocks extended planning (14-day forecasts), unlimited history, deeper insights, pattern recognition, year view visualizations, and 10 curated themes. But the core experience—session tracking, safety warnings, and vitamin D estimates—is always free.

Important: Hello Sun provides estimates, not medical advice. Always listen to your body, protect your skin, and consult a healthcare provider for personalized guidance.