Ask HN: What are some of the best written macOS apps?

I'm looking for github repositories of applications. Note, I do not care how many stars/forks a repo has or how useful the application itself is. I'm looking for well structured tested code that can serve as a reference to write a macOS application.

I don’t have any off the top of my head (helpful... I know), but I do have a tip that might save you some headaches down the road:

Remember to support Case Sensitive file system partitions.

This has bit me A few times and is a very annoying bug to trouble shoot down the road if you aren’t consistent with your naming structures.