Josh Bloch refactored libraries in Java that handles a bunch of data structures. It was widely considered a success and he teaches API design at CMU (was also an engineer at Google):
https://www.youtube.com/watch?v=heh4OeB9A-c&ab_channel=Googl...
https://www.cs.cmu.edu/~charlie/courses/15-214/2014-fall/sli...
These use Java as the language, but a bit of this applies to web APIs as well.