Parhélie: Find when another city sees your exact same sun

Hi everyone, Parhélie answers a question I couldn’t stop thinking about: the sun I see today — where and when does another city see it at exactly the same height in the sky? It computes solar elevation using the NOAA algorithm (≈0.1° accuracy) and finds the precise dates and local times when another city matches it. It also gives the two annual zenith passages for tropical cities, plus solstices and equinoxes recalculated each year. Two things I’d like to mention up front. First, it’s a PWA — no App Store, no Play Store. You open it in a browser and add it to your home screen; it then works offline. Second, the city database covers 7,774 cities above 80,000 inhabitants, hosted with the app itself, so no third-party calls when you search. One personal note: everything — design, code, testing, deployment — was done from an iPhone. No computer at any point. I’m a public health physician by training, so this was my first time building the instrument rather than using one. It’s 0.99 €, one-time. No subscription, no ads, no tracking. I’d love feedback from anyone who wants to challenge the accuracy.