GeoSync is a city comparison app that lets people search two cities and view their boundaries side by side at the same real-world map scale. try it at https://geosync.willstark-lab.workers.dev The idea came from a simple curiosity: wanting to compare places I already know, like two cities, neighborhoods, or familiar locations, at the same scale without manually matching zoom levels across separate maps. GeoSync turns that spatial curiosity into an instant side-by-side comparison, making it easier to understand how places relate in real-world size. On the technical side, It normalizes OpenStreetMap/Nominatim geometry, computes area, bounds, and centroids, keeps MapLibre panes scale-locked, and generates shareable comparison URLs with OG preview images. And hosted on CloudFlare.
