I am particularly interested in knowing about developers using Java, Python and Scala. Would also love to know about contributors to Machine Learning libraries.
Depending on the language you are interested in, look into following core contributors of the most popular backend frameworks in that language.
Gergely Polonkai
You have to believe in things that are not true. How else would they become?
I don’t think you should follow developers, but projects.
If you are interested in back-end development in general, you are in trouble. I can give you a list of about 15 back-end framework in multiple languages off the top of my head, and if you start following all their core contributors, you are facing a list of at least 60 people.
What you should do instead is
At the end, you will have a bunch of people with interesting side projects. It worths noting that many of such side projects will not be related to back-end development, or even web development at all. Taking myself as an example, if you look at my GitHub and GitLab accounts, you won’t find too many web-related repos, but they still might be interesting to you.