I made this mistake many times - Ramadan in Iraqi Kurdistan, Formula 1 blocking Monaco, 48°C in Kuwait on cheap July tickets. Traveling somewhere without knowing what environment I will land into, So I built a travel calendar that shows everything at once: festivals, public holidays, weather, visa requirements, crowd seasons, travel warnings. Tech: Python FastAPI backend, no database - just static JSONs. All data from free public APIs (Open-Meteo, python-holidays, passport-index). 400+ festivals with schedule algorithms (Hijri, Easter, lunar). 250 destinations, some splat to biomes for better advices. Hosted on GCP, costs almost nothing to run. No registration, no paid APIs, no affiliate links. Just a hobby project from a guy who’s been to 90+ countries, got tired of surprises and who’s sitting in Frankfurt airport waiting for his flight to Addis Ababa.