format xml, pretty print

Well, the identity transform you linked to is portable to any XSLT processor (Saxon, msxml, etc).

Additionally, you could look at xmllint which is part of the LibXML2 toolkit. The --format option allows you to pretty print the input. Similar functionality exists in XMLStarlet (which uses LibXML2 under the hood iirc).

xmlstarlet fo is what I use for pretty printing. Xmlstarlet has a number of options:

$ xmlstarlet fo --help
XMLStarlet Toolkit: Format XML document
Usage: xml fo [<options>] <xml-file>
where <options> are
  -n or --noindent            - do not indent
  -t or --indent-tab          - indent output with tabulation
  -s or --indent-spaces <num> - indent output with <num> spaces
  -o or --omit-decl           - omit xml declaration <?xml version="1.0"?>
  -R or --recover             - try to recover what is parsable
  -D or --dropdtd             - remove the DOCTYPE of the input docs
  -C or --nocdata             - replace cdata section with text nodes
  -N or --nsclean             - remove redundant namespace declarations
  -e or --encode <encoding>   - output in the given encoding (utf-8, unicode...)
  -H or --html                - input is HTML

A good XML engineer should be able to wield xmlstarlet.

You can use http://prettydiff.com/?m=beautify Unfortunately, it is written in JavaScript, but it is a complete application so you never have to know that. Just know that you can run from inside your browser without downloading or installing anything.