Good steps to take in the article. But I'd also add that Django REST Framework, which they seem to be using, has throttling capabilities built-in which I would have attempted before changing the API: https://www.django-rest-framework.org/api-guide/throttling/

Adding pagination seems reasonable, but it may have broken clients who didn't expect pagination to be there.

Hi! Thanks for the recommendation, I did go with that approach

Offer something in exchange for emails. Maybe a short tutorial packaged in a PDF?

Django because there are a lot more resources, and the community is pretty welcoming to beginners -- so it's very easy to find help.

If you are in need of a beginner-friendly tutorial, I would recommend the Djangogirls tutorial.