I'll be flying to Edinburgh for the Fringe Festival in a couple of days, and I've been putting together a much better app than the official one. It builds the full catalog of shows as a sqlite database and syncs it to your phone so that you can filter, search, sort, and build a schedule even with the traditionally spotty data during the fest. I also added a bunch of coordination features for planning your Fringe with friends.
Not officially, but I did add the ability to drop shared pins on the map for your friends. I also had that in mind, some of the most fun or wild moments have been on the street.
It's a PWA, not a native app over at https://fringeflypost.com/ (or you can go directly to https://fringeflypost.com/shows to browse if you don't want to make an account.)