In my experience, relying on "prettifier" websites is directly a result of the lack of canonical, well-supported CLI tools for prettifying most programming and markup languages. It's such a weird glaring gap in dev tooling.

I'd love to see "standard" prettifiers for HTML, CSS, JSON, YAML, and TOML. The required libraries exist and the problem isn't terribly hard if you aren't picky about corner cases. I'm sure countless programmers have written such tools already. Where is the disconnect?