I am looking for PDF anonymizer software that will automatically remove potentially identifying metadata.
It must be free as in beer, and it must run on OS X.
It does not need to be perfect; this is for convenience, not for legal applications.
Command line tools are okay for as long as they don't need arcane syntaxes to achieve this goal. Ideally it should be a tool purpose-made for this. It is possible that this is achievable with Ghostscript with complicated command line options, but I can't keep those in mind, so it's not what I'm looking for.
Adobe Acrobat does this but it is not free.