I'm curious why you decided to move APIs from Django to Flask? We've built our APIs on Flask, and, though I like Flask a lot, the major complaint is that there's no real story around user authentication and authorization, endpoint versioning, and a handful of other things that aren't directly serving the purpose of the API, but are important nonetheless.

There are a hodge-podge of plugins to do various things, but they don't necessarily share the same design principles or work well together. Some are so abstracted that by the time you've got a concrete implementation you could have just rolled your own.

EDIT: Grammar, added a sentence.