These are tools that I use on a regular basis. I’ve left out common tools (Git, macOS, Docker, …).
Alfred (macOS; productivity app) gives me the power to do all the things I want, right when I need them, without introducing clutter. I have a handful of custom workflows tuned for the way I work, which I imagine impresses my coworkers.
OmniGraffle (macOS) is the best diagramming tool I know of. It isn’t cheap, but I find the $100 price tag to be worth it. I use it to impress my coworkers.
Visual Studio Code (cross-platform) is my editor of choice. I switched from Atom, which by itself is already an amazing piece of software, to Visual Studio Code, which is at the same level of awesomeness.
Fastmail provides excellent email, but also web hosting and DNS management.
fish shell is a fast, easy-to-use shell that has sensible defaults. I have barely customised it.
ripgrep is my command-line grep alternative of choice.
xsv is a must-have tool if you deal with CSV files. I think CSV is a pretty good format!
hamster provides efficient immutable data structures (which are sometimes more efficient than built-in Ruby ones).
ref provides a soft ref implementation, which is indispensable for effective memoization.
RuboCop indispensable when writing Ruby code. It pretty much eliminates all discussions about style.