Docker would be on the list for me - for reproducible environments.
Probably JUnit as it was my first real testing framework - for being able to use test driven development for hard problems.
With programming, I had so many "aha"-moments, it's hard to remember them. It's not all about software, but more about understanding the concepts and being able to transfer this knowledge. Being able to pass functions or function pointers. Streaming / piping data instead of a fixed data structure. Interpreted vs compiled languages. How everything we do here only happens through a long list of 0s and 1s and how this clever setup makes us even see graphics on the screen. Or hear audio through a screen reader....
With programming, I had so many "aha"-moments, it's hard to remember them. It's not all about software, but more about understanding the concepts and being able to transfer this knowledge. Being able to pass functions or function pointers. Streaming / piping data instead of a fixed data structure. Interpreted vs compiled languages. How everything we do here only happens through a long list of 0s and 1s and how this clever setup makes us even see graphics on the screen. Or hear audio through a screen reader....