Hammerspoon is one of my favorite tools. I especially like the low latency of the system hooks, other tools like Automator or Folder Actions have a couple second delay betweeen the trigger and the action. Hammerspoon is pretty much instant.

On top of that, Hammerspoon is very actively developed and the maintainers are super knowledgeable and responsive.

I've shared a couple scripts on here before, like Anycomplete (Google autocomplete anywhere): https://news.ycombinator.com/item?id=13065670