I am a Full-stack/Cloud software engineer so it should be related to my position, but not strictly. Let's say it can be iOS/Android/Web development, Back-end development, Machine Learning, Cloud Architectures, Theoretical Computer Science, Cybersecurity, etc.
After some research, I have found most of the resources are already free. I have had an idea to buy several classical CS texts (specifically related to Math Logic and Complexity) or purchase some online courses, but I can miss something valuable. Maybe it can be useful for somebody to suggest decent resources I can spend this bonus.
For example, I bought Practical Common Lisp despite it also being available electronically for free, because I tend to write a lot of margin notes and highlight things that I know I'll want to see again. It is so much quicker for me to pick that book up and get to the info I want than it is for me to scroll through a PDF for the same info (besides lacking my personal notes). I have multiple random electronic copies I don't bother looking at, and one printed one that I refer back to quite often.
If you want to take some courses in complexity, check out complexityexplorer.org. They are run by the Santa Fe institute, so you know they're top of the line. You can generally take the courses for free since they are offered through grants, but of course you can donate and/or buy some schwag to support more of their (incredible) course and tutorial offerings. I just finished a course with them today, actually, and am working on completing a third from them.
Is it restricted to only those? And there's plenty of self-published books on leanpub/gumroad (usually with sample chapters provided).