[leni536]

I have mupdf in firefox (iceweasel) using mozplugger. I could always set it up to not display pdfs, only downlad them, use mupdf through mozplugger or use the builtin pdf.js viewer. Having said that I'm not sure that mupdf is safer than pdf.js, but it's much faster.

[baghira]

I was debating the merit of having the pdf reader bundled and on by default, instead of having the pdf file downloaded like most other files. One can certainly change firefox's behaviour in the settings (unlike webgl).