This is the Stylish project as a whole, linking to the individual language bindings and the editor integration.
A historical note:
Stylish used to be Perl-only and Emacs-only, but now it has branched out. The Emacs stuff is at https://github.com/jrockway/stylish-elisp and the Perl stuff is at https://github.com/jrockway/stylish-perl.