I've been maintaining for 6 years this Dog API that only returned facts. I recently rewrote the project to make it more flexible [1] and I had a blast doing so.
This API has been used by a lot of computer science students, as well as bots and other 3rd party services that integrated in the past. The old endpoint receives around 1,000-1,500 requests per day, which makes me happy.
The goal is to extend it to make it more interesting and usable, I collect dog data in my spare time. I'm not looking to monetize it, it's just for the love of education.
Feel free to use it, and share it!