Jetlag Coach
After ~20 years of long-haul travel, I spent the last 9 months building Jetlag Coach, in parallel with my busy life (full time job toddler and pregnant wife!). You give it your chronotype and your actual itinerary (multi-leg and layovers included) and an optimization engine generates a personalized schedule for light, sleep timing, caffeine and melatonin to shift your circadian clock toward the destination time zone. At core it turned out to be a complex optimization problem and a real challenge to tackle. I also put a lot of care in the UI/UX, while I usually focus more on backend work. It's working well, I am just finalizing the handling of some of the nastier edge cases https://www.jetlagcoach.com