In regards to pretty-printing XML/HTML, if I'm writing it by hand, I take care to write it cleanly, and if I'm generating it with a module, if I need it to be human-readable, usually those modules have options to format it (e.g. XML::LibXML::Document has ->toString(1) or ->toFile($filename, 1)). Other than that, many IDE's have built-in pretty-printers (when I was coding more Java, I used Eclipse a lot, it's also good for editing/formatting XML).