How to reverse the page order of a PDF file?

PDFtk can also do this (it’s available in most distributions as pdftk):

pdftk myfile.pdf cat end-1 output myfilereversed.pdf

One can make use of pdfjam which provides a front end to the "pdfpages" LaTeX package (and thus comes for example with texlive).

It generally allows to create a new PDF file by selecting pages from multiple PDF files. Particularly it allows to specify decending ranges, using "last" to refer to the last page:

pdfjam myfile.pdf 'last-1' --outfile myfilereversed.pdf

reverses myfile.pdf.

For further possibilities see pdfjam --help and the documentation of pdfpages.

You can use qpdf:

qpdf --empty --pages infile.pdf z-1 -- outfile.pdf

You can find more information here on page 11.