> > I have created one
https://c.albert-thompson.com/latex-pretty/ It
> > focuses on indenting blocks. It does not check syntax though.
>
> The answer is much the same as it was in 1990: most
> [La]TeX-sensitive editors do something like this already. Emacs is
> possibly the locus classicus.
Actually a pretty-printer would be quite useful for formatting
machine-generated LaTeX code. When a script auto-generates LaTeX
code, it's cumbersome to do good indenting, and well-formatted LaTeX
within the script often uglifies the shell code that produces it.
So a pretty-printer is a good idea. But bizarre that it's a web tool.
This means using it for machine-produced code entails web-scraping.
It also means the content is shared with the webmaster. Ideally
someone would expand on an existing pretty-printer tool like /tidy/
(an HTML pretty-printer).