Where can I find good code to read and learn.

Not the best, at least not my department. Could have been done better. I also wish to rewrite some of our codebases.

Ah yes the classic, this code is shit let's rewrite it from scratch. Tread carefully. Good read if you have some spare time: https://www.joelonsoftware.com/2000/04/06/things-you-should-never-do-part-i/ I applaud the effort to learn how to write better code, but at the end of the day, the best code is code that serves the business need and exists. For Java specific, some good resources are "head first design patterns" and "effective Java" (disclaimer: I haven't finished or gotten very far in either) or if you're looking for more high level structure see if you can find a open source project that tries to do similar. I've found open source projects to high good code organization simply because it's necessary to allow so many collaborators (caveat, open source level quality is probably way overengineered for any project that only has a handful of engineers) Edit: also Google "<technology> boilerplate" e.g. "spring webservices boilerplate" for inspiration

Cassandra Airflow etc?

Sure if that’s most interesting to you. They have atleast 100, and 15-20 are extremely popular.

Yeah what's the googlyness score of this stack ? Care to cite some good GitHub repos for me to read?