This is a Heroku buildpack for MuPDF.
heroku create -b https://github.com/motdotla/heroku-buildpack-mupdf.git
# or if your app is already created
heroku config:add BUILDPACK_URL=https://github.com/motdotla/heroku-buildpack-mupdf.git
git push heroku master
Use heroku-buildpack-multi to combine this buildpack with others. For example, carve-worker does this.