Around that time, I serendipitously stumbled upon Kiwi.com’s Tequila API, which includes—almost as an afterthought—an endpoint that returns all the destination cities for a given origin and set of dates. This presented an interesting possibility: take a few origin cities, find all the destinations for each, filter down to the overlap, and sort the results by total flight prices.
I initially prototyped FlightJive in 2020 (lots of spare time on my hands) and just got around to finally fleshing it out.