In situ Syntax Highlighting in macOS Applications Like Keynote

Earlier this month, I returned to CSS Day for the first time since 2018 to deliver my first in-person talk since 2022. “Forging Our Own Paths” should be available at some point; in the meantime, for the six or seven people in my audience who might need to do something similar, I’d like to share a small macOS workflow I developed to make syntax-highlighting code blocks in situ in Keynote a lot simpler. The end result is to have an entry (or entries) in the Services submenu of the contextual (right-click) menu for highlighted text. All this is adapted from an old blog post I found copied in a few places, and which needed some updates to make things work in 2026. This is what it looks like for me. It could look much the same for you! First, install highlight. I used brew install highlight, and the rest of this piece assumes you’ve done it that way. If you install it another way, such that it ends up in a different location than Homebrew would give it, you’ll need to modify a variable…