Where do you get the data from? This incredibly useful!
Passport data largely from https://www.passportindex.org with fallback to Wikipedia scraper
Monetary per diem estimates come from a multitude of sources and then blended together into a interpolated raster which the backend uses to query so that there are no empty spots for cities with no data.
Transit connection estimates are based on GTFS and airline sources
I also expose some of this data in my other tools:
- Reverse flight search https://unli.xyz/flights/
- Gap year planner https://unli.xyz/city/calc/
Your website is a really good idea. I always refer to Wikipedia to know the entry requirements for Canadians, because embassy websites do a terrible job of sharing the most basic information.
I always wanted to build a technical travel atlas that would give basic information like power socket type, average weather, driving requirements etc. It would be a lot better than relying on a bunch of wordy travel blogs. If the APIs are there, it would be very doable.